Nagi's younger sister and the partner who supports the strongest assassin, "Tank Chair." Burdened by the guilt that she is responsible for her brother's current condition, she continues to provide constant care for him while he remains unconscious. Believing that "exceptional murderous intent" against Nagi will restore him to his former self, she leads him into battles against formidable enemies under the guise of "rehabilitation."

A Class A student at the Academy. He specializes in assassination arts that involve erasing his presence, utilizing the ability of the "Migraine Mollusk"—a semi-biological creature parasitic to his brain. In exchange for using this power, he is constantly tormented by excruciating headaches. He harbors a fierce rivalry toward his former classmate, Nagi. He cherishes his younger sister, Touko, to an obsessive degree and will stop at nothing to protect her.

Naozumi's younger sister and, like her brother, a Class A student at the Academy. She fights by temporarily enhancing her physical abilities through the inhalation of a special gas from a cylinder she wears. Although she expresses her emotions only through a "Shooo" sound, she is able to communicate perfectly with her brother. She has absolute trust in Naozumi and fights alongside him as his partner.

A genius scientist who lives in hiding inside a ruined radio tower. Using a technology that remotely controls animals through brain waves, she commands chameleons, dogs, crows and the like, monitoring everything happening across the city through their eyes.

A mysterious newcomer who has joined Class A at the Academy. He harbors intense rivalry and murderous intent toward Nagi, driven by the goal of becoming the "perfect being" that Sensei will acknowledge. Cruel and pleasure-seeking by nature, he possesses immense latent potential much like Nagi, and relentlessly hunts down the Taira siblings.

The founder of the Academy—an absolute ruler wielding overwhelming power and a fathomless, unnerving presence. Forever in search of a "perfect being," Sensei shows an abnormal obsession with Nagi.

The standard configuration of the combat wheelchair piloted by Nagi. Equipped with blades on both arms, it is designed to shred through enemies. It is even capable of superhuman feats of mobility, such as scaling vertical walls by deploying spikes from its tires.