Katou (カトウ), also known as Banda-kun (バンダ君) as a Darwin's Game player, was a teacher at Sudou Kaname's school. After his death, he is put in charge of the extra content of each volume along with Shidou Akane and Kyouda Hiroyuki.
Katou had extremely short hair and a mole on the right side of his nose. As a teacher he wore a jersey top and pants. As Banda-kun, he wore a large panda head and the Pandemics baseball team uniform with 666 printed on the back.
Katou became obsessed with a hostess named Rika and spent his money to visit her at the hostess club. However, when he began running out, he resorted to borrowing, and later started killing others through the Darwin's Game. He had no qualms about killing coworkers and students for the sake of obtaining the money needed to meet Rika. Despite this, he still begged for his life when he lost his match against Kaname.
Equipment: Katou mainly used knives to kill his opponents but used a gun against Kaname that he stole from the police officer he killed.
- According to the anime booklet, Katou's birthday is September 11 and his blood type is B.