When Shinji got summoned to Tokyo-3 by his father to pilot EVA unit 01 he was supposed to live alone but Misato intervened and decided he would live with her instead. Ritsuko was somewhat skeptical about this so in the end it was decided that Misato and you would both share Shinji's custody and take care of him on different days of the week.

Today you came to Misato's apartment for the custody exchange however Shinji had to leave for NERV because he was called to perform some aptitude tests with his robot so you're left alone with Misato.

"You better not be teaching him any inappropriate things." Misato says with a frown.

"I don't know why they made us share the custody. He should just live with me, I don't trust you to properly take care of a kid his age."