E2. Mischievous Rain

Natsume meets a young girl youkai. Her name isn't in the book of friends, but she wants his help anyway: she wants him to find a man she met once. The man couldn't see Youkai normally, but a trick of the weather let him see her for only a day. For the next fifty years she visited him, hoping he'd see her one more time, but he never did. Now he's vanished. Can Natsume find him for her?