Tank Chair

Taira Nagi, once the strongest assassin, was confined to a wheelchair after falling unconscious protecting his younger sister, Taira Shizuka. Shizuka works as an intermediary for assassins, taking on assassination requests and taking her brother to the battlefield under the guise of "rehabilitation." Hoping for her brother's full awakening, Shizuka accepts a request to eliminate Arashiyama Goro, the boss of a vicious gang of robbers.

In order to help Nagi's rehabilitation, Shizuka searches for someone with a stronger killing intent and sets her sights on Takanashi Ryo, a highly skilled sniper. Takanashi is a madman who is only interested in "good targets." Shizuka asks Takanashi to snipe Nagi, plotting to awaken Nagi's true nature through his intense killing intent.

Nagi and Shizuka's former assassin training institution, "Gakuen," is pursued by the siblings Kurosaka Naozumi and Touko, who arrive on Guichen Island. The A-class students suspect that the numerous "strange killings" occurring on the island are Nagi's doing and begin their search. Shizuka encounters her former classmates, Naozumi and Touko, who press her for Nagi's whereabouts, putting her in a life-or-death situation.