Once upon a time, in a land far away that was divided into two realms...
The Outside was roamed by teratomorphic creatures who had the power to curse whoever they touched. Humans could live safely only in the Inside. But when a lost little girl from the Inside named Shiva, and a demonic beast-looking Outsider simply known as "Teacher" initiate a quiet coexistence on the same side of the forest, their bond seems to transcend their incompatible natures. It is the beginning of a folktale about two outcasts -one human, one inhuman- who linger in the hazy twilight that separates night from day.
(Summary Courtesy of MyAnimeList.net)
10-minute OVA that premiered on September 10, 2019.
Animated by Wit Studio.
See also:
Totsukuni no Shoujo (OVA 2)