Kinji and Mutou are somewhat close friends that was formed after having a dueling event called, Lumberjack, during their freshman year. They talk normally in class and out, and seemingly done missions together before. Mutou along with Shiranui like to tease Kinji of his relationship with women.
Mutou seems to have some sort of crush for Shirayuki, and is most likely aware of the fact that Shirayuki has absolutely no interest in him at all. However, it is suggested that Mutou only likes Shirayuki for her appearance only and not much else.
Mutou and Shiranui are good friends, who like to tease Kinji of his relationship with women.
Mutou and Hiraga are teammates on Team Carrier GA.