In the wake of her grandmother’s death, Tsugumi Dozono, who used to work at a large electronics company in Tokyo, decides to move from to the home her grandmother left behind, in the countryside, and work from home. One day, a mysterious middle-aged man named Jun Kaieda arrives at the home wanting to stay the night. He tells Tsugumi that he is her grandmother’s ex-student and her grandmother gave him a key to the annex house. Tsugumi doesn’t quite understand the nature of the relationship Kaieda had with her grandmother, but the two begin living together in an awkward arrangement. Based on the manga series "Otoko no Isshou" by Nishi Keiko.