Natsume's Book of Friends (2008)

S5E2 Mischievous Rain

On a gloomy, rainy day, Natsume encounters a young girl youkai who seeks his assistance. Although her name isn't listed in the Book of Friends, she has a special request: she wants him to track down a man she met long ago. This man, unable to see youkai under normal circumstances, was granted a brief glimpse of her due to a playful twist of fate. For the past fifty years, she has returned to visit him, longing for another chance to be seen, but he has since disappeared. Will Natsume be able to locate him for her?