|Occupation||Candidate for King of Celestial World|
|Previous occupation||Teacher of Hinokuni Junior High School|
|Japanese voice actor||Katsuji Mori|
|English voice actor||Ben Jeffrey|
Kobayashi (小林), a.k.a Mr. K (Kobasen (コバセン, short for Kobayashi-sensei (Teacher Kobayashi)) in the Japanese version), is a teacher at Hinokuni Junior High School. Kobayashi is also a candidate for King of the Celestial World who gives Ueki his power. He is Ueki's homeroom teacher and had been carefully studying him in order to judge his worth for the tournament.
Kobayashi is usually a laid-back, forgetful, and friendly man, although he can be quite serious, depending on the situation. He has a very strong sense of justice, actually inspiring Ueki long ago when he saved him from falling off a building, and acts as both his mentor and role model. He is sent to Hell for saving (and thus helping) Ueki in his first fight against Robert Haydn. He then become Mori's god candidate.
It is mentioned in the show that Kobayashi's least favorite food is fried crickets in soy.