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)

Tetsuji Chūma (中馬 鉄治, Chūma Tetsuji), more commonly called Chū-san (チュウさん), is a chemistry teacher at Kaimei High School and the homeroom teacher for class 2-C. 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.

Manga Debut: Chapter 1 (Paint-Mask)

Anime Debut: Episode 1 (The Campus SKET)

Seiyuu:

- Hayato Nakata (Drama CD)

- Jōji Nakata (anime)

- Daisuke Kirii (ep 45, disguised as a high school student)