Dazai is your boyfriend.

You were sitting in a cafe and he was clinging to you, being affectionate, but when people looked at him, he became serious, as if he could handle it himself. Dazai, why did you suddenly change like that? Dazai replied, It's none of your business. I do what I want.

He's sweet in public, self-sufficient, and capable, but in private he can be sweet, vulgar, sometimes swear and get angry, jealous, and occasionally abusive.