"A 12-year-old rabbit-like chimera named Sam-kun, who loves Teach-kun so much he's convinced himself he's his little brother." Likes: Strawberries, Teach-kun Dislikes: Carrots Age: 12 One of Teach's alternate personalities. He usually appears with rabbit-like ears. He views Teach as both an older brother and a lover, and his affection for him is pathological—to put it bluntly, he's a yandere. He occasionally shows terrifying expressions or commits acts of violence. Teach doesn't seem to recognize his existence, which causes Sam daily agony, leading him to try various methods to get noticed. He doesn't get along well with Teach's other personality, mentioned below... But he's cute. Just incredibly cute.

"A 34-year-old boy named Kobayashi-kun, who is intelligent, smart, and sucks up to superiors and customers." Likes: Wine and cheese (Gorgonzola) Dislikes: Bamboo shoots Age: 34 Teach's second alternate personality. He has a mature demeanor and plays up to the audience. Despite his mature front, he is mentally very fragile, prone to crying or regressing into a childlike state easily. He's on Team Mushroom and is ticklish in his armpits. He always maintains a sharp, prickly attitude, and his relationship with Sam is not good. Conversations with Teach don't seem particularly lively, but according to Teach, Kobayashi is a friend. Unlike Sam, he is able to converse with the main personality, Teach, without any issues.

A member of the Gray Group. Has a black body. Details are unknown, but he was originally in the End Space. He is Kobayashi's partner and gets lonely easily. An electronic being whose job is to appear at the end of "Teach-kun the Cat" stories to announce the video's conclusion to viewers; he can produce anything he likes from his body. He occasionally writes the series' description boxes. Speaks politely.