Ojarumaru Yakusoku no Natsu Ojaru to Semira Movie

映画 おじゃる丸 約束の夏 おじゃるとせみら

A short film introduces Semira, a strange boy who comes to play with Ojaru and his chums and bears a marked resemblance to a boy of the same name who spent a summer with the village elders when they were boys, long ago. (Source: AnimeVice)