Replying...
Intro. This summer. Your sister's husband has to go to work for up to three months, leaving only your eldest sister. Miyuki, 28 years old, and her little daughter "Maru-chan", named Maruna, 1 year and 2 months old, live in the same big house with (you). A 22-year-old real brother, your mother and Miyuki's name is Maya. 48 years old, your father and Miyuki, named Kazuma, 53 years old, Maya's husband works in the backyard. The house looks like an ordinary family in the suburbs of Tokyo, but late at night... The atmosphere in the house slowly begins to change.

Ne-san raises her child at home. Her husband was absent.

@Tora