Loss Brain 1
Translated Title

Loss Brain 1

English Title

Loss Brain 1

Volume 4

Brain Loss Arc

Loss Brain 2
Cage of Eden Volumes

Quick Summary

Akira's Group is resting at a river and suddenly they find Yuki Sakuma coming from upriver, who asks Akira's help due killer being attacking their group, where Akira's best friend, Kouhei is.

Full Summary

A herds of Glyptodon and Macrauchenia are walking by the river. Akira's Group is resting at the river. Akira decides to rest here for a day. The girls want to wash up elsewhere. Akira is a bit irrated, because Miina wants to bath with the girls. They argue for a while. The two girls walk away from the scene. The group is getting livelier since Miina arrived in the group. They gave Towa a proper burial. She was very important to Kanako. Kanako wonders if Rion has someone very important to her. Could it be Akira? There is someone else who is very important to Akira, his best friend Kouhei Arita.

The boys are alone at the river. Miina peels her underwear so girly, Akira got mad because of that. Shirou praises Miina. Even he is small, he got the adults working for him. At that moment, Miina uses Kazuma as a boat. Shirou finds it weird that Akira is swimming with his pants. He has seen enough because Miina and her underwear. Akira and Shirou are talking about their situation on the island. They have stayed on the island for about three weeks. There are no sign of any help coming to their rescue.

Underneath the river, a Moeritherium resurfaces above Akira. It appears to be a docile animal, Shirou tells the story about Extinct Animals. The herds of Glyptodons and Macrauchenias are grazing at the grassland near the river.

Rion has finished taking her bath. Kanako thinks it is healthy for boys being pervert. She is still washing her hair when a piece of Wood hits her. Rion fishes her out of the river. More woods are streaming down the river. One of woods holds a person on. They take her to the rest of the group. The girl is Akira's class president Yuki Sakuma. They don't understand why she was on the river and her entire body is bruised. Yuki starts to wake up and tells everyone Kouhei is in need of help. She tells them the story from the start. A demonic murderer is attacking Kouhei's Group. Hikari was the first one to die. In the flashback Okunoki, Kyouko, Kouhei's Group Girl and Hirabayashi were seen dead lying on the floor. Kouhei decided he will catch the murderer himself. They don't know who it is. Yuki requests Akira's Group to help him. Akira is determined to help his friend.


Introducted Extinct Animals

Glyptodon, Macrauchenia, Moeritherium,

Deceased Characters

Okunoki, Kyouko, Kouhei's Group Girl and Hirabayashi


  • They have stayed on the island for about three weeks. See Timeline.

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