Her Granddaughter (Otoko no issho)

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.