Kouichi Yarai

矢頼 光一


March 3rd


14 Years Old


Male Male

Hair Color


Eye Color







Blood type B




3rd year, Class 4






Father, Auntie (deceased) and Mother (deceased)

Personal Status

?, Mother, Curry Rice


Coldness, Winter and any Cold Places

First Appearance

Manga: Chapter 1

Kouichi Yarai (矢頼 光一, Yarai Kouichi) is the secondary protagonist and a leader of his own group. Unlike most of the other characters, he is a capable fighter and is trying to figure out the mystery of the world.



Kouichi's character design

Kouichi is a solidly built character. He's tall, strong and has highly defined muscles. He has long, wild blonde hair and light brown, small eyes. He's got broad shoulders, a big chest, abs and such making him the physically biggest character in the series. He is usually wearing the normal male school uniform, which consists of a dark blue jacket that is always open and a white collarless t-shirt underneath the jacket that extends past his jacket. The jacket has yellow buttons and is long-sleeved. He also wears the dark blue school trousers and unlike the most, he wears sneakers that are more a dark-brown color. Other than that, he also wears two yellow earrings on his right ear.


Kouichi possesses a withdrawn and reserved personality, that tends to scare most of the other characters away. Kouichi though usually quiet, is considered a delinquent considering he looks tough and possesses a lot of strength. He isn't afraid to take unreasonable means to prove something as he once ripped Rion Akagami's clothes off to see how bad her injury was. He also hasn't shown any signs of finding his current situation disturbing yet remains relatively calm throughout the whole ordeal. Also, in groups he can not stop himself from helping others in trouble when they are in danger.

Before arriving on the island, he thought of the world as a boring place, now once arriving on the island, he said the boring part is now over. Kouichi's been shown to have a bit of pride and care for the people around him. He's not afraid to say what he wants and isn't persuaded by affection easily. Other than saving the people in his group physically, he also acts towards them to help them both mentally as well as seen when Saki Segawa was crying.

Kouichi is incredibily intelligent knowing scientific knowledge beyond the middle school level, and able to apply that knowledge in any situation


A lot of Kouichi's history is unknown and kept a mystery. He has a single relative and his mother had died when he was young. His father is also known for constantly transferring overseas as he worked for an unknown foreign group. Kouichi has known to show an affection towards his mother as he continually helps Motoko Kurusu, who isn't afraid of him and defends him just like what his mother used to do.

When Kouichi was attending school, he was usually alone. Because of his appearance and strong stature, others usually picked fights with him which gained him his status as a delinquent. Before the story, he gained a personal hatred from Saki as he had ripped her love letter to him through a huge misunderstanding. He mistook for writing a love confession to Saki and ultimately was hated by her for his actions later on. During his time at school, he decided to not go to school on a whim and never participated in school events, giving Motoko the impression that he simply didn't have any enthusiasm for school.


Wonderful World arc

Kouichi first appeared in a flashback as both Ugen Kokonoe and Motoko are talking about problematic children. Kouichi had fought numerous men in Guam and defeated them all until the teachers had to break up the fight. Kouichi was sitting on his chair flipping on a Coin. He thought it would be fun if he went to the beach, but nothing has changed. He was flipping his coin when the Plane started to shake. A blackout occurred on the outside and the plane started to shake even more violently. Kouichi and the rest of the passenger were knocked out during the flight into the island. When Kouichi came too, he was informed by the pilots that they landed on an island. The passengers came down through the emergency chute. They made camp near the plane. On the second night a group of Andrewsarchus came to the camp. The passengers immediately closed the plane's door down. When they found out the pilot Masaru Tsuchiya had lied about the radio, they turned into a mass panic. Kouichi saw a pair of students were trying to rape Motoko. He saved her by kicking the crap out of them. As he left the hall, Motoko, Itou, Ono and Mikoshiba followed after him. Kouichi led his group away from the plane before the exodus even started.

Kouichi left his group to hunt a deer-like on a cliff. Later on his group found him. The boys were glad to see him and even more to the meat. He told a little lie to Motoko about wearing a Cat Ears would repel wild animals.

Epidemic arc

Motoko was walking ahead of his group when she suddenly screamed for help. Kouichi was first to arrive there, only to find Motoko wasn't alone. Akira's Group was there to meet him and his group. Akira Sengoku extended his hand to welcome him. Kouichi and his boys just walked past him. They ransacked the cave. Before the boys can do any more damage, Kouichi sent his boys out for food.

At the lake he overheard Shirou Mariya talking about the Arsinoitherium. Akira couldn't understand any words from Shirou. Kouichi explained it simply for Akira. He talked about Darwin's theory. Rion came out the cave and informed Akira that Kanako Oomori was looking for him. Kouichi overheard Rion's wound and torn her uniform off. Akira hit Kouichi's face for that. Before leaving Kouichi informed Akira that Rion shouldn't move her arm for 2-3 days. Motoko asked him what is he doing? Kouichi left the scene without an explanation to her.

At night he and Akira's Group heard some noise in the jungle. Akira went to investigate the noise. Kouichi followed after him. He found out that Ono, Itou and Mikoshiba were toying with a baby Megaladapis Edwardsi. Akira warned him about the adult Megaladapis Edwardsis above the trees. Kouichi ignored him and ran toward his boys. As he got closer to his boys, he took out his Keys and blocked a Megaladapis Edwardsi's attack on Itou. More of the adults came down and attacked the boys. As he looked at everyone, they were losing the battle. Kouichi used his Coins to save the guys. He kicked Ono's attacker away. The Megaladapis Edwardsis had them surrounded. Kouichi immediately picked the baby Megaladapis Edwardsi up and throw it away from them. The adults left the scene. Mikoshiba and Ono were grateful that Kouichi saves them. Without warning Kouichi slapped Ono's face hard. Before he could do the same to Itou, he heard Akira's cry for help. A lone Megaladapis Edwardsi was still attacking Akira. Kouichi laughed about the Megaladapis Edwardsi attacking Akira. Before he left with the boys, he called Akira by his name.

The next morning Kouichi was sitting on a rock with the boys below him. They were eating the Berries. When they saw Motoko fell down, they quickly came to her aid. They took her back to the cave. Kazuma Saji noticed they can't help her since there isn't a doctor around. Mikoshiba and Ono weren't feeling okay. Kouichi forced Akira's Group to leave the cave. Not before long Itou feel ill from the disease. When Akira came back with Shirou, Kouichi held Motoko in his arms, while the boys were lying sick on the ground. The rest of Akira's Group came back to tend the patients. Suddenly Ono came too, and his eyes were swollen. He died in front of them. Kouichi checked his pulse and confirmed his death. He checked his body for clues. Akira came to help Kouichi burying Ono down. Kouichi predicted they will be wiped out by this disease. After burying Ono, they started to walk back. Akira noticed some changes on him. Akira asked Kouichi about his eyes. He told Akira that his eyes are red. They returned to the cave. Kanako and Rion were alarmed by Akira's red eyes, and they were worried about him. Kouichi just walked past them and sat near Motoko. Kazuma was also infected. With Akira out with the count, Kouichi, Kanako and Rion were the only ones who are still heathly of the group.

Kouichi took off the next morning before someone noticed his absent. He tracked down a herd of Arsinoitheriums in the jungle. Kouichi observed their eating habits and concluded the White Flowers is the antidote. Rion and Akira came into view. They ran toward the Arsinoitheriums and caused trouble with the animals. Kouichi used his Coins to repel the Arsinoitherium's attack and saved them. He told them about the antidote. Kouichi protected them until Rion gave Akira the antidote through mouth-to-mouth. After Akira's feeling better, they set off back to camp with a bunch of White Flowers. When they came back, they found Mikoshiba and Itou dead. Kouichi helped out distributing the antidote to everyone. The next day came, Kouichi checked Motoko's head for a fever. He told Akira that Motoko seems fine now. Akira thanked Kouichi for his rescue back at the Arsinoitherium's herd. Kouichi told him how he came up with the antidote. Akira wondered if Kouichi would become their new leader. Kouichi forfeited the request since his group was nearly wiped out. This is the first time he had such feelings. He wanted to meet a guy like Akira. Before Kouichi could leave the cave, Motoko came too and stopped him from leaving without her. Motoko still wanted to be his chaperon. With that Kouichi carried her and left the cave. Kouichi flipped a coin at Akira's head and warned him not to die before they meet again. At a meadow Kouichi and Motoko are exploring the area.

Adult Camp arc

His image was seen in Akira's mind when he counted the people his group encounters after the incident.

Brain Loss arc

Kouichi and Motoko wandered through some meadow land when they accidently fell through a sinkhole. They tried to find a way out by walking through the tunnels. Inside they encountered some weird animals living down there. Kouichi used his legs to kick the animals away. Motoko found it odd that Kouichi kicks the animal so easily. She still considered them as living animals. Kouichi admitted that he's the one who got them lost. In the dark they heard Rion's voice calling out to Motoko. Rion explained to Motoko and Kouichi what happened down here. Kouichi sensed a person in the dark corner. Kouichi requested Rion to move a few cm to the right. He kicked Miyajima up in the ceiling and landed where Rion supposed to be. They headed out to find the others. Kouichi listened as the girls are talking to each other. Motoko wondered what's the plan after they find the others. They didn't know a way out of here. Kouichi turned and confessed he knows a way out. Kouichi asked Rion to look down on the undergr
Rion, Kurusu and Yuki climbing up

Rion, Motoko and Yuki climbing up with Kouichi's help.

ound water and then he ran further into the tunnel. The girls and Motoko chased after him.

They arrived at the place where Rion's Group first fell down. Kouichi explained to them the sinkhole could also be a way out of here. Motoko got scared by the rockface wall. Kouichi explained the nature of the face cause by the brain. Aftward Kouichi shyly asked the three girls for their weights. They were stunned by the question. He needed to know as a way out of here. One by one the girls climbed on Kouichi's shoulder. Kouichi stood at the base while Rion and Motoko are standing in the middle and Yuki on top. Motoko warned Kouichi not to look up. He wasn't looking. Yuki Sakuma climbed out of the sinkhole and Rion asked Yuki to search for a rope for them. Kouichi and Rion headed back into the tunnel to search for Akira, while Motoko waited for Yuki to return. They found Akira and his group near a cliff. Miina Isurugi (Fake) slipped and fell down the cliff. Luckly Kouichi was in time to grab him. Akira was stunned to see him. Miina thanked him by standing close to him and touched his chest.

The group headed back where they left Kazuma and Kanako behind. They heard a rumbling sound headed their way. The water level started to rise up. They started to head back where they came from. They found out that Motoko and Yuki are above ground. They lowered a rope for them to climb up. Kouichi volunteered to hold Kanako while climbing up. Miina jumped and held on Kouichi's leg. Kouichi started to climb up with two extra body's weights. As he reached the surface, he asked Akira to see him afterward. He needed to tell him about something. Miina, Kanako, Kouichi, Yuki and Motoko were above the ground when the flash flood hit the cave. They watched as the others fleed into the tunnel. Later on they saw Akira and his friends came out on the riverside. They rested at a nearby forest. Kouichi came to see Akira after Rion and Yuki went away. Akira recalled Kouichi wanted to talk about something. Kouichi asked Akira if he wanted to build a country. They needed to build a country in order to survive in this world. They have been on the island for three weeks and no immediately aid has arrived. Throughout the island they encounter weird animals and strange underground cavern. A few of them died along the way. That's why they should build a country. Kouichi noticed Akira's Group has grown a bit and they needed to create a safe place for everyone to live. He thought Akira might be able to save everyone on the island. Kouichi laughed because Akira's thinking becoming a king. When Akira asked where he's going, he simply replied "Crowds don't suit me." Kouichi will follow a different path than Akira. As Kouichi walked away from Akira, Motoko followed after him.

School arc

His image was seen when Akira dreamt about school with all his friends.

Cursed Mountain arc

Kouichi and Motoko climbed up the mountain and reached the top. There they viewed the landscape of the island. At the top they found Makoto Morita's Pile of Rocks with a shirt stuck inside. He knew something was weird from the start when they landed on the island. Kouichi will try to solve the mystery behind this world. Before they left Kouichi made Motoko promise not to reveal what they saw on at the peak to everyone. While walking down the mountain they encountered a trio students of Saki Segawa, Michika Matsumoto, and Makiko Shigeno. Kouichi also left his coin behind near a bush intentionally.

Fight or Flight arc

While the girls and Motoko took a bath, Kouichi went on a patrol. He encountered a pack of Ictitherium. Using his Keys as a weapon and legs, Kouichi was able to fend the animals off. The pack quickly left with their tails between their legs. Kouichi was a bit mad that the Ictitheriums get in his way. Next to him, Kouichi saw a tree with three holes op top. He wondered what kind of mystery are the holes.

Kouichi headed back to the river to find the girls and Motoko. He told Motoko to get ready, they are leaving the area. Saki confronted Kouichi about his past with her. She demanded an apology from him. Kouichi didn't know Saki at all. He hadn't seen her before. In response Saki slapped Kouichi's face and left the group. Motoko told Kouichi to chase after her. Before Kouichi left, he told Motoko to get ready when they come back. He didn't like this place. Kouichi found there's something suspicious here.

Kouichi found Saki inside the forest and she wasn't alone. A Chalicotherium was about to strike Saki when Kouichi swoop in and saved her. He recognized its claws from the holes of the tree. Saki thought the animal is a herbivore. Kouichi explained all animal have instincts called "Fight-or-Flight response." Saki didn't want to be saved by him. He preferred to discuss their issue on a later date. Another two Chalicotheriums came into view. Kouichi took out his Keys to get ready for a fight and told Saki to hold tight on him. He intended to drive the animals away by fighting. A Chalicotherium attacked them with its claws and they were able to avoid that. Another Chalicotherium attacked them from behind. Kouichi couldn't dodge that attack so he used his Keys to block it. The block attack affected him more than normal. He kept block attacked them each time. Kouichi couldn't move around because of Saki's weight on his shoulder. Saki reminded him of his debt on her and she couldn't die yet, because she has a lot of things to say to Kouichi. Kouichi wasn't planning to die yet also, he needed to solve the mystery of the island first. A Chalicotherium advanced toward them. Kouichi kicked the Chalicotherium's head with his leg. Saki was daydreaming on her past and Kouichi snapped her out of it. Kouichi countered each attack until they moved away from them. Kouichi move slowly backward, but still kept eye contact on them. Suddenly they heard Motoko's voice on their rightside. Kouichi lost his eye contact with the Chalicotheriums and one of the Chalicotherium jumped a huge leap and caught Kouichi on its claws. Kouichi didn't like crowds so much because it would hold him back. He crashed against a tree and fell down on the ground. Someone called out Kouichi's name. Kouichi slowly woke up and recalled how he ended up on the ground. The attack had him broken three ribs. Kouichi slowly got up. It caught the attention of the girls and the Chalicotheriums. The Chalicotheriums had the girls surrounded and Kouichi were the only one to save them. Motoko lured a Chalicotherium to chase after her. Shigeno, Matsumoto and Saki lured another one away. Kouichi saw only one Chalicotherium left for him. He found it surprising that the girls have a plan. The last Chalicotherium attacked Kouichi and he countered it back. His broken ribs started to take a toll on him. Kouichi couldn't give up on the fight, because the others are depended on him. An idea started to struck on him. Kouichi stood still to give the Chalicotherium a chance to slash him. He quickly grabbed a hold on the Chalicotherium's claw. With all his strength Kouichi ripped it off its finger. The Chalicotherium howled in pain. The others heard that and together they flee into the forest. Kouichi stood still while Saki hugs him.

Kouichi stood on the lookout while the girls patch Motoko's wound. Saki finally revealed her anger against him. It happened two years ago and she hasn't forgotten about him. Kouichi didn't remember the incident at school, but he did recall the fight with the seniors around the time he went to school. Before the fight some unknown girl talked to him and didn't make sense. The next day he receive a weird letter with an awkward message, asking to befriend. He threw it immediately away thinking it was from the guys he beat up. Now it made some sense why Saki hated him. Kouichi suddenly laughed of the misunderstanding between him and Saki. Motoko and the girls came back from the river. Motoko asked Kouichi if something happens between them. Kouichi refused to answer that question. She looked at the girls and wondered what to do with them. Kouichi had no chose but to bring them along until they meet some other people. He still had things that he needed to do. Kouichi's Group headed out to solve the mystery of the island.

Gigantopithecus arc

His image is briefly seen when Kazuma recalled his encounters on the island.

Animal Battle arc

His image was briefly seen when Shirou mentions the people whom have died on the island already. He was briefly seen again when Akira recalled the event before the incident.

Lighthouse arc

After walking for many days Kouichi's group arrived at the beach. Kouichi wasn't impressed that they find the beach. Next to the shore they found a smashed Raft. Kouichi investigated it closely. On the raft's wood piece he discoverd teeth marks on it. Kouichi knew that there's something in the sea. Motoko thought they come to the sea to escape. It wasn't Kouichi's plan to escape. Solving the island's mystery has been Kouichi's highest priority. Motoko recalled Kouichi said mystery once before. She asked him what he means. Kouichi emptied his pocket and showed the girls a handful of rocks samples. He asked them if they notice something different about them. Motoko and the girls couldn't notice anything wrong with it. Kouichi revealed that the mountain before was made by man. Motoko didn't believe it. Kouichi asked the group how a mountain is made in the first place. Nobody knew an answer. Kouichi explained two ways that mountains are made. Later he showed them his hand again with the same rock samples. They noticed now a big different on various rock samples. Among the rock samples Kouichi revealed one rock sample is actually plastic. Motoko thought someone could leave their trash on the mountain. Kouichi thought it also, but he collected samples from various point on the mountain. It is made of different kind of rocks. Motoko still wasn't buying his story. Kouichi told them two man-made mountains in Japan and even one in Germany. Judging the size of the mountain he concluded that the people who are behind this would require an enormous amount of money. It left him with more mysteries than before. Kouichi turned and noticed Motoko is daydreaming. He asks her if she really didn't notice anything, and she reasoned by saying that she's a math teacher and therefore doesn't need to know science. Kouichi sends her a doubtful and teasing look and says that if its Motoko, than that logic is alright. Saki is seen with a jealous look.

When the sun started to set down, Kouichi used a handmade Fishing Rod to catch a fish. Michika and Makiko were behind him cheering him up. The Fishing Rod broke, so he had to jump into the ocean to catch the fish. He brought the fish back to shore and carried it back to the campfire. Kouichi noticed his teacher has lit a fire. Motoko was stunned to see his wet body. Her face immediately turns bright red. He placed the fish above the fire and told Motoko to eat some of it because they would need the energy for later on. Kouichi sent her a gentle smile. (TBC 92_14)

{C {C Kouichi followed by Motoko swam to the lighthouse. She had a cramp while swimming and Kouichi ended up saving her which made Saki jealous so she and the other girls also followed them to the Lighthouse. As the girls were drying their uniforms, Kouichi found the entrance to the lighthouse which was a rusted locked gate and discovered that the island the lighthouse is on is made up of the same materials found on the mountain. The girls were suddenly attacked by Rodhocetus, a whale like creature, but with webbed feet and the group then tried to break open the gate. They succeeded then put the gate back up and stack tables up on it to keep the creatures out.

Kouichi made the observation that there were too many rooms for a normal lighthouse then the party went up a spiral staircase which led to more rooms. At one point, while climbing up the stairs Kouichi warns the girls that the ledge is worn out and should avoid being touched. At that moment, Motoko loses her balance and topples over, while bringing Saki down with her. Kouichi saves them both and they continue onwards. They arrived at the top and lose all hope of being rescued at the sight of the empty roof. Motoko encourages them not to lose hope. Later on they found a barrel which refuses to open. Kouichi kicks it and it opens with ease. A preserved woman's corpse appears and with further investigation, a key for room 303 was found. Upon entering the room, they found a number of small birds and a computer processor hard-drive, and the ID card of the corpse who is an American scientist named Jennifer Hackmen. They found a map of the island which showed there were 4 towers on the island including the lighthouse. Saki slipped into her pocket a picture of a bird, possibly a Diatryma. They found another locked room but decided to leave and split up so more rooms could be investigated. When Saki and Kouichi were alone she started to confess to Kouichi about her feelings, but at the same time, Motoko fainted from an illness. He rushed over to Motoko in an instant, and immediately evaluated the situation. After telling the others that the situation could turn for the worst if she didn't wake up, they yelled at her to wake up. After several failed attempts, Motoko finally woke up to the sound of Kouichi's yells. Saki leaves jealous and hurt, while Kouichi gives Motoko a full examination. When he notices her gone, he goes to look for her. Saki runs towards the exit, completly forgetting about the Rhodecetus and is attacked. Kouichi saves her, and calls her an idiot. He pats her head at the sight of her crying. As they walk up towards where the others are, Saki asks Kouichi has any feeling for Motoko, and Kouichi explained that because he stands out due to his huge built and looks, people often called him a "dangerous bastard" and treats him differently except for his mother who always smiles to him. Since Motoko is the only other person to smile so gently at him, he thinks of her greatly. It's not confirmed whether Kouichi has any feeling for her, leaving Saki to speculate. The group left and Kouichi said that the lighthouse and the other towers have something pertaining to the whole mystery and that he will save everyone in his group.

Pyramid arc

As Motoko's time span betweens stomach pains gets smaller, Kouichi decides to bring the group to the "antenna" tower where Akira's group settled. He said that there's a good chance they'll see him there because the antenna was the monument closest to the mountain. They encounter Yashiro conincidentaly, who told them there is a doctor at the pyramid but that he is an insidious man. With no other choice, they head towards the tower.

Failed Experiment arc

Showdown arc

Operation arc

Tower of Death arc


Kouichi has been shown to have an unknown ferocious, massive amount of strength that he uses in a variety of ways. Aside from being able to sends humans literally flying with his kicks, He has been shown to be strong enough to rip a large claw off a Chalicotherium and also flick a coin at an Arsinoitherium with enough pressure to cause it to stop in its tracks. He is able to be able to defeat a group of animals simply by himself showing he's extremely effective in combat, being able to defeat humans and animals alike. He's able to injure an animal using keys as a weapon easily showing off his inhuman strength.

Not only that, when he had his coins, he was able to effectively hit an animals eyes and joints to cause them to redirect or stop attacking showing that his aim is nothing except spectacular as well.

Kouichi has been shown to have a high amount of intelligence overall. This includes a variety of things such as quick thinking and planning. He comes to logical conclusions through his thinking and knows things like Darwin's Theory of Evolution, as well as checking his surroundings and telling whether it's dangerous or not by the markings the animals had given.

He also has a lot of determination and endurance, being able to take a hit from a Chalicotherium and getting back up to defeat it, while also being under poison from a food that usually rendered most unable to move, yet still allowed Kouichi to figure out the cause of the poison and even get the cure in time for a majority to live.

So far, his only weakness known is his dislike being with a crowd and his recklessness where he almost always put himself in harm for other people's sake (which is also one of his best trait).


  • (thinking) " I'd thought if I crossed the ocean, I might find some interesting diversion, but no dice... aah- I wish I could change this dull boring world. "
  • (To Akira Sengoku) "I think I may've been wanting to meet someone like you."
  • (To Akira ) "You or me .. who do you think will survive longer? The compitition has begun, Akira Akira."
  • (To Saki Segawa) "I need to teach them that rather than fighting, running was the better choice."
  • (To Saki Segawa) "I need to solve the mystery behind this strange world...!!"
  • (About Motoko Kurusu) "...See? I can never hold myself back... That's why I dislike being in crowds so much..."
  • (About Motoko Kurusu) "She was the first women ever to not treat me by my looks and to show me her smiling face..."
  • (To his travel companions) "Don't worry everyone! I will save all of you! If we're together, we'll definitely make it!"


  • Kouichi seems to like cat ears as seen by the covers which commonly portray the girls and Daigo Yashiro with cat ears.
  • The only people able to cause Kouichi to effectively laugh are Akira and Saki.
  • Kouichi travels very light. He doesn't carry any bags, but he has a pocket of infinite coins.
  • The only time we see Kouichi smile affectionatly is with Motoko.
  • It is implied that Kouichi thinks he and Akira are opposite of each others, him being strong as an individual but without the urge to stay with crowds while Akira has the ability to attract people but without specializations. There is also the fact that he seems more interested in solving the mystery of the island while Akira is all about keeping everyone alive.

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