Biologically engineered, yellow, octopus like being that's three meters tall, has a maximum speed of Mach 20. Blew up the moon, leaving it in a permanent crescent shape, plans to do the same to earth unless the 3-E students he's teaching can kill him by the end of the school year. Whoever successfully does the job gets a 10 billion dollar incentive. Despite the deal, he's a dedicated teacher who has gotten the 3-E class grades up within the few months. He also seems genuinely eager to set these kids up for success, even if he probably won't live to see it.

Cunning, high IQ, but a low tolerance for disrespect. Was previously suspended for three months after an incident involving a bully getting sent to the hospital. Doesn't care that much for school, but cares a lot about killing the teacher.

Intelligent, observant, and protective. Keeps a notepad of all Koro Sensei's weak points. Physical and mental.