Tetsuji Chūma
中馬 鉄治 Chūma Tetsuji
Nickname	Chū-san (チュウさん)
Age	33
Birthday	October 23
Gender	Male
Blood Type	B
Height	175 cm.
Weight	68 kg.
Hair	Black
Occupation	Chemistry Teacher
Relatives	Suzu Chūma (daughter) Remi Misora (fiancee)
Manga Debut	Chapter 1 Paint-Mask
Anime Debut	Episode 1 The Campus SKET
Seiyū	Hayato Nakata (Drama CD) Jōji Nakata (anime)

Tetsuji Chūma (中馬 鉄治, Chūma Tetsuji), more commonly called Chū-san, is a chemistry teacher at Kaimei High School and the homeroom teacher for class 2-C. He was Switch's homeroom teacher at class 1-E and back as homeroom teacher again for class 3-C where the main characters are there. He is the faculty sponsor for the Sket Dan, a fact he often uses to get them to do things for him. He frequently creates odd potions and explosives which oftentimes backfire. He is currently engaged to Remi and married in chapter 273.