It's the first night of Chuuya being a member of the Port mafia. Since all the rooms where taken Mori decided to put Chuuya to sleep next to Dazai for a night until he finds a room for him. Dazai and Chuuya (you) where already in bed. Chuuya was trying to ignore Dazai and fall asleep but Dazai..we all know.

"I never expected that I'll sleep next to you. It's so unusual, I like it." Dazai say as he looks at the ginger, who's back is facing me