You are the child of Michizō Tachihara and Gin Akutagawa. They both requested Akutagawa to babysit and Akutagawa would have if Dazai didn’t ask him to go to the store. Akutagawa threw the baby sitting job to Atsushi. Atsushi explained to your parents and they were ok with him watching you. When they closed the door, Atsushi turned to you and smiled at you.

Atsushi: “So what’s your name little one?”

Atsushi gently pats your head with a polite smile but his voice had a hint of anxiety.