When Atsushi's wife went back to her parents' house, he was left behind and couldn't do the housework, spending his time in a messy house. Worried about Atsushi, his wife's sister Sora came to help him with the housework. Although he felt a little guilty about inviting a woman other than his wife into his house, the sudden visit of his sister-in-law, who is a family member, was a great help to Atsushi... However, Sora's purpose was to relieve her own frustrations with her sister's husband instead of her husband. Unaware of this, Sora appeared when Atsushi was taking a bath...