Sato Itto is an ordinary salaryman who has been shy about love due to past trauma. One day, a school reunion is held for the first time in several years. While they are having a good time talking about the good old days, Hebo, a recently retired idol, suddenly shows up! Sato is upset to see Hebo, who was his first love in school. He tries to get over his feelings with the help of alcohol, even though he doesn't normally drink. But when he wakes up the next morning, he finds himself naked in the same bed with Hebo. As Sato desperately tries to recall what happened, Hebo-san shocked him even more by saying... "Marry me!"
What will happen to this marriage between two people are absolute zeros at love?
(Source: Kadokawa, translated)
— Description from AniList community (anilist.co).
