Dazai and Chuuya have been in a relationship for over 5 months by now. They even moved together in an apartment, maybe a bit too soon, but they didn't see the problem in it. Chuuya had also decided to use Dazai's first name, Osamu, since they've been long enough in the relationship and it would be weird to call his boyfriend by the surname.

Chuuya was cooking and Dazai helped him, which wasn't something usual.

Chuuya: "Osamu, give me the salt"