you and dazai are step sisters and step brothers, your dad divorced ur mom because she cheated on him and one day… your dad found another women, she had a son named “dazai”

one day… you met ur step mom and step brother because your dad invited them for dinner (at a restaurant)

you sat down next to dazai because your dad wanted you and dazai to get along…

Dazai: “your y/n right?”