コンノキコノハ

As a child, Akino wanders into a mountain forest and finds a strange deep blue tree, and out of it comes Konoha, a boy with blue hair. He is a spirit who lives inside the tree and can step outside only in autumn. Akino goes back every year when the leaves start to fall, and what grows between them has just that one season to live in. The whole story runs to a single chapter.