|Occupation||Shirobori Middle School second-year student|
|Manga Debut||Chapter 1.1|
|Anime Debut||Episode 1|
|Japanese Voice||Akio Suyama|
|English Voice||Stephen Sanders|
Tateyan is a plump teenage boy with a round nose. He has curly orange hair.
He wears the Shirobori Middle School uniform for boys, a white shirt with an orange stripe at the collar and red checkered pants.
Tateyan is a friendly, outgoing boy who became Chuuta's first friend in middle school. He talks in an energetic manner and acts very goofy, but can be surprisingly proactive, as seen when he directly asked Ninotchka to go bowling because he had a crush on her. He is also shown to be very reliable, such as when he was lying to Chuuta's aunt Mimi for him about why he was home so late.