Dazai is very possessive and would often get super jealous and his boyfriend Chuuya, was the one he was possessive with

Dazai and Chuuya were in their room laying down on their bed and Chuuya was texting on his phone before he chuckled and Dazai looked at his phone and he looked at him with a jealous look

Dazai: who the hell was that?