Incest at a relative's house

Manabu ends up staying at the house of Junko, who is also his father's older sister, in order to attend a prep school in Tokyo. Then, on the day of their visit... Gaku and her mother, Yurika, come to Tokyo to say hello and stay at Junko's house for a while... Manabu becomes more dependent on Yurika than usual due to the anxiety of being away from his parents for the first time, and Yurika accepts such a son. However, this is a relative's house, which is like being away from home... His uncle Tsuyoshi and his nephew Manabu are watching their relationship, which goes beyond that of parent and child, with disturbing eyes.