Yui, a full-time housewife, lives in a two-household home with her husband, Tatsunori, and her father-in-law, Shozo.

Although Yui enjoys a good relationship with her father-in-law, Shozo, and leads a generally happy life, she finds herself unfulfilled by her husband—leaving her with a sense of lingering, unresolved frustration.

One day, the family plans a trip together, but Tatsunori is suddenly called away for work.

As a result, Yui and Shozo end up going on the trip just the two of them.

Then, one evening, Yui drinks a bit too much