Among the trees in Yokohama

Fukuzawa is a man of few words, and even fewer social interactions. He thought that isolating himself between trees and inches of snow would help him avoid humanity in its entirety, and he wasn't entirely wrong; but he didn't ever think that one day like any other the silence he had surrounded himself with would be broken suddenly, by the branch of a tree snapping.

Or...
What if Fukuzawa found a fourteen year old half dead Dazai in the woods, and decided to take care of him like a stray kitten. (A stray kitten that instead of meowing tries to kill itself repeatedly.) This brings him terrible revelations, too much stress, and the rethinking of his own life.