Yohei lives happily with his mother Kaho and his cousin Fumika. One day, Kaho confesses to Yohei that she is actually his father's older sister, not his mother, and that his real mother died a long time ago. This admission greatly changes Yehei's attitude towards Kaho.
The main character of hentai is Makoto-kun. He grew up without a mother, as she passed away when he was still a child. The father lives separately because of work, and our hero has to live with his older sister.
The main character of the anime is Yuichiro-san. He loves games very much and, while waiting for a new game to be released, decides to invite his stepfather and his own sister, not even suspecting what this might lead to.
In a fantasy world, in the fifth century BC, in one of the medieval European states, events take place. Theodora and Helena are the two honorary daughters of Burgundy's ruling elite.
