Nice Guy: He's too nice for his own good. This is how his eccentric classmates flocked to him in the past.
Only Sane Man: He's the only normal person in a building full of eccentric people, and has had to deal with eccentric classmates with unique quirks back in middle school. This trait actually lands him a job set up by a Sumiko and her friend.
Episode 3 shows her trying to apologize for bluntly rejecting Usa's offer for a bike ride, but after a while she starts rambling, eventually leading her to clearly wondering why her words aren't coming the way she wants them to.
Only Sane Man: Next to Usa, she may be the only normal person in a building full of eccentric people.
Butt-Monkey: Shares this with Usa, but Shiro enjoys it thanks to his masochism.
Chivalrous Pervert: He's a perverted masochist, but is still a nice guy. He's also quick to voice his dislike of molesters, and treats Chinatsu's Precocious Crush on him like a phase she's going through.
Cool Old Guy: Probably the second oldest person living in the Kawai complex, and despite his perversion, he does share a few words of wisdom to the other tenants.