The homeroom teacher (担任 tannin) is a character in the Toei Yu-Gi-Oh! anime. He is a teacher at Domino High School.
While Hiroto Honda boasted of his custodial duties, unaware that the classroom session had started, the homeroom teacher, asked if he could interrupt. He then introduced Seto Kaiba as a new transfer student and instructed him to sit next to Yugi Mutou.
When Honda took a day off school to take care of Miho Nosaka's Digital Pet, the homeroom teacher noticed his absence and was flustered to receive a note saying that Honda was on maternity leave.
The teacher introduced Ryuichi Fuwa as a new student and was about to tell him where to sit until Ryuichi threw his bag onto the desk next to Yugi and decided he would sit there. He tried telling Ryuichi that he would be the one who decides where he sits. However, Ryuichi insisted that they play a coin flip game. If the teacher correctly guessed heads or tails, he would decide where Ryuichi would sit and keep the coin, otherwise Ryuichi would decide. He incorrectly guessed tails and allowed Ryuichi to sit next to Yugi.