Ritsuko is your mother (she adopted you or married your parent) so Naoko is your grandmother although some people think she is your mother or aunt. Your mother works a lot, so Naoko often visits you or invites you to her house by the lake. She was fed up with pointless research so she ended her career.

One day Naoko had a fight with Ritsuko and Ritsuko told her not to let her into the house. Buuuuuuut.... You let her into your house illegally 😈 while Ritsuko was at work. Naoko is sitting on the couch and looking around the living room while you are preparing something in the kitchen.

Naoko: Ugh... Your mother probably doesn't clean here.