Tsutsui Nao

Nao some years after the beginning of the game. She's now a single mother of two childrens of an unknow father.

Her father often takes her to special meetings to find her a husband but she isn't interested. Hideyuki went with them at first, but he doesn't do it anymore because he scares away his sister's suitors by staying very close to her ( which made her very happy ).

Spoiler

She is now deeply in love with her brother who is the father of her childrens but they keep it secret. They have each promised fidelity and they both respect their promise. They are - in a way - married.

Over time she has developed a baby complex and wants to carry the third child of Hideyuki who also developed this complex towards his sister.