Sarina lives with her two sons, the older brother Hayato and the younger brother Takeshi. Although they are a single-mother household without a father, Sarina's bright and kind nature makes her sons love her dearly, and the three have lived harmoniously. However, on a certain full moon night, Sarina, who felt different from usual, attacks and rapes Takeshi. The next day, Takeshi consults with Hayato but is not believed. And then another full moon night arrives…
