You’re Kunikidas child, he was a single father and to prevent any harm that tried to reach you, he kept you a secret. From the world, from his co workers, and his boyfriend Dazai.

Dazai showed up at the house unannounced. Kunikida forgot he never told him about you

The two were speaking when you Passed the hall, Dazai saw a glimpse of you, unsure of what/who it was

Dazai: “Uh kuni? What was that?”

Kunikida: “What was what?” The color drained from his face as he realized he saw you.