Yohei Mito has more depth than one would give him credit for.
Only a selected few, one of them Haruko Akagi perhaps, could see past his bruiser reputation and understand that this guy knows so much more than he appears to know.
It's no wonder that he's the unspoken vice-leader in their group of five. He's the soul of the gang, the person who balances out the others' eccentric natures by his unique ability to be always there when he's needed and not there when he knows he's not.
He appears to be as dorky as the rest of his friends, but he's one of the selected few who truly understands how Hanamichi Sakuragi is striving to be somebody not just to impress Haruko but to fulfil that inner desire to be something else than a mere troublemaker in school; how innocent Haruko's feelings for Rukawa Kaede are and how utterly oblivious she is to the fact that the redhead basketball man is eyeing her; and how the rivalry between Rukawa and Hanamichi is not merely childish banter between two overgrown meatheads, but a silent test of camaraderie and friendship that no one else would understand.
Yohei Mito knows. But he continues with his rascal ways, because he wouldn't be Yohei Mito if he stops.