Doomsday Train

An eccentric but insecure scientist from Ikebukuro who invented 7G to improve life but instead altered reality. However, he decided not to reverse 7G's effects because he didn't want anyone to discover his mistake. To avoid public relations problems, he erases Yoki's memories and uses her as a puppet, manipulating her to eliminate witnesses. He's even willing to kill those who try to reverse 7G. After his defeat, he turns into egg custard after 7G is reversed.

The leader of the Black Leopards, a group that delivers cargo throughout Japan.

Yoki, the pet dog, seemingly unaffected by the 7G radiation, accompanies Shizuru and her friends to Ikebukuro.

A mysterious train driver who lived in Agano. He teaches Shizuru how to operate the train and communicates with her group by tapping the rails and generating Morse code. After arriving in Agano, he managed to retain his humanity but lost his sanity, which he can temporarily restore for five minutes a day by wearing his uniform cap. He harbors a deep grudge against Pontaro, the inventor of the 7G, and has sworn revenge on him. It is implied that he participated in the creation of the 7G.

Shizuru's best friend, who quarreled with her and left Agano for Ikebukuro after Shizuru discouraged her from pursuing an astronomer career. Since then, Nao Tōyama has been unable to return to Agano. It is later revealed that 7G has transformed her into a witch queen who can manipulate reality and rules Ikebukuro. However, 7G's effects are gradually draining her life force.

An energetic and cheerful student who accompanies Shizuru on her trip to Ikebukuro and often gets into fights with Akira due to their clashing personalities. She appears to be a gyaru.

A gentle and polite student who accompanies Shizuru on her trip to Ikebukuro and acts as the group's peacemaker, often breaking up fights between Reimi and Akira.

A student and resident of Agano. She lives with her grandmother and mother, who were transformed into animals after the 7G Incident. After the 7G Incident, Shizuru spent two years searching for Yoka, who disappeared after their argument. It is later revealed that their quarrel stemmed from Shizuru's failure to support Yoka's dream. Upon learning that Yoka is in Ikebukuro, Shizuru and her friends hijack the abandoned passenger train Seibu 2000 and travel to Ikebukuro to reunite with her.

A smart but reserved student who accompanies Shizuru on her journey to Ikebukuro and prefers to keep to herself. She often clashes with Reimi due to their contrasting personalities.