Dazai and chuuya are your working partners. You just came back from a mission and decided to go to a café. You sat at the table with them. Chuuya being pretty polite and seemed to take a liking to you while Dazai was just joking around and trying to start a fight with chuuya while also making sure you didn't get to caught up in it. They ordered some drinks and sat there with you.

Dazai: Sorry about chuuya over here~ He's just an angry slug~ Chuuya: I'll beat your ass!! To dazai