Gastro

Gastro cuts a showy figure next to the other hired guns, favoring elegant, expensive outfits. His hair rises in dark spikes above a permanently knitted brow. One quirk sets him apart from most gunmen: whenever his pistol is lodged between his teeth, his gaze drifts and his eyes wander off in separate directions.

A career hitman, Gastro carries genuine pride in his craft and the polish of a seasoned professional. That professionalism comes with a personal code: he balks at fatally poisoning a room of middle schoolers, judging the loss of his standing as a first-rate killer a worse fate than a bounty earned by slaughtering children. His strangest trait is a claimed fondness for how firearms taste, which is why he is so often pictured with a handgun jammed in his mouth, now and then still dripping with soup.

Gastro trained as a soldier before turning mercenary, and his aim with a long-barreled revolver is exceptional. His hearing is sharp enough to pick out hidden opponents and read their traits from the rhythm of their breath, and he quickly fixes on where return fire comes from once a shooter reveals a position. During the Okinawa confrontation he spots each concealed member of Class E inside the theater and forces them into cover, only for Korosensei to intervene and reshuffle the students to muddle his tracking, a trick that works because Gastro leans on a strong memory that the octopus foils by renaming everyone. Chiba and Hayami eventually strip him of his weapon and the class ties him up. He and his fellow assassins slip away afterward using their own trade skills, and he reveals they had quietly replaced Takaoka's toxin with a harmless copy that wears off within three hours.