Soukan no Akai Kashi

Overview

Totomi was abandonned by her parents and has to live with his uncle Kaname since her childhood. In love with each other they will end up in an incestious relationship while knowing that this won't last forever. When Tomomi has to meet Shinji, her fiancé, they see the opportunity to end their relationship, but the link that unites them is much stronger than social conventions

Source: AniList