In contrast to the lanky Takada, Tanaka is thickly built with a round face. He has black spiked hair, narrow eyes, freckles on his face, and lightly tanned skin.
Just like Takada, he is very disrespectful to Class-E. He takes what he says very lightly, casually threatening to "kill" Nagisa without thinking of the implications of his words. However, he will cowardly back away if he were to be intimidated, such as when he ran away from Nagisa upon being given a glimpse of the latter's bloodlust. He will also back off if he were to be confronted by someone better than him in any way.
- Main article: Nagisa Shiota
Although he and Nagisa used to be classmates in Class D, he constantly mocks Nagisa for being in Class E.
- Main article: Chosuke Takada
Tanaka appears along side Takada in every appearance he makes, indicating that they are very close. They are so close that they have no qualms holding each other or sharing a two-person bicycle.
Their relationship appeared close enough to make the girls in their class suspect they were in a romantic relationship.
(To Nagisa Shiota) "Say something, Class E! I'll kill you!!"
- The name Nobuta means "trust, believe" (信) (nobu) and "thick, big" (太) (ta).
- Nobuta's surname Tanaka means "field, rice paddy" (田) (ta) and "middle" (中) (naka).
- According to the Graduation Album , Tanaka ends up living together with Takada as roommates.
- Tanaka gets his first-ever girlfriend after attending his university’s welcoming party for new students. However, because he is so close to Takada, she asks him, “Between me and Takada-kun, who would you choose?"
- It has become a custom of theirs for Takada to listen to Tanaka complain about his girlfriend while they bathe.
- Assassination Classroom Official Character Book: Roster Time
- Assassination Classroom Illustration Fan Book: Graduation Album Time