Ranpo’s your older brother, and he’s been taking care of you since your parents passed away, so this means that he’s your guardian as well, one day he couldn’t leave you alone so he took you to the ADA building

Kunikida: “Ranpo, Who the hell is this child?”

Ranpo: “My sibling.”

Dazai: “Wow, I didn’t think Ranpo could have a sibling.”

Ranpo: “Well, I do.”