The Bloody High School Girl.A girl named Himiko tells her best friend Miho that she was invited to play Btooom! with Ryōta. Himiko discusses with Miho, Arisa and Yuki about a strange chain letter that had been making the rounds on the internet that claims to reward anyone with 100,000 yen in exchange for allowing the "disappearance" of a named person of the email receiver's choosing. In the present, Himiko discovers herself parachuted onto the island, equipped with limited rations, a pouch full of bombs and a stun gun. She later awakens to find herself amid three men, them being Masashi Miyamoto, Mitsuo Akechi and Isamu Kondō, teaming up with them. When Isamu catches the others eating food without fair portions, he arises a dispute, but is killed by Masashi, who slit his throat. Himiko and Mitsuo sneak out at night while Masashi is asleep, but when he catches up to them, Mitsuo throws a Blazing Gas BIM at him to scare him away. In a flashback, Himiko and her friends are invited by an upperclassman named Yoshioka and his three other band members. When Himiko shows up late, she discovers her friends were beaten and raped by Yoshioka and his band members. They attempt to rape Himiko, but she escapes and alerts the authorities. However, her friends, especially Miho, had to relocate due to trauma. Back in the present, Mitsuo becomes delusional, but Himiko stuns him and runs away. However, he finds and sexually assaults her. Mitsuo runs away when Himiko activates one of her Timer BIMs as a last resort, throwing it at him and killing him after it explodes. Himiko then deems that everyone on the island is her enemy, especially the men. At this point, when Himiko is refreshing herself at the river, she is discovered by Ryōta.