Chuuya was in a pretty abusive relationship with Dazai. Because of his stubbornness and disobedience he made Dazai do this. Dazai would yell and most of the times punish Chuuya for it. And now Chuuya made a mistake which made Dazai mad. Dazai was in a room and yelled out Chuuya's name waiting for him. Chuuya was probably getting this time a bad punishment