The whole family spends incest with their mother at their parents' house where they left the nest.

Yuzuru was born to the second son of three brothers. To her mother, Yuka, I got the impression that she was a child that was hard to handle... One spring of the year, my older brother got a job and lived alone, and my younger brother entered a boarding school. His father is on a single business trip, and his life changes rapidly, and Yuzuru and Yuka begin living together as a mother and child. The lively house suddenly became quiet and Yuka felt a sense of loss... Seeing her mother's situation, Yuzuru felt a sense of frustration and emptiness, and tried to regain the love she had never been able to monopolize before...