After losing his mother, Masahiro lives with his father. His father is unable to balance work and childcare on his own, and Masahiro lives a NEET life. Then, his father remarried and Anna, who became his stepmother, comes to live with him. Anna is shocked to see the dilapidated state of the single-parent household, and begins by cleaning up Masahiro's room in an attempt to improve his life. However, Masahiro becomes increasingly resentful of Anna for invading his territory, and plots to harass her in an attempt to push her away...