Reo Za Kaindo Wāurufu

Reo za Kaindo Wāurufu (レオ・ザ・カインド・ワーウルフ, lit. Reo the Kind Werewolf) is a 66 episode anime series created by Japanese studio, Andromeda Animation that first aired in 1979 and ended the following year.

Plot
The series is about a little girl, Reo, whose parents had abandoned her after she was born, who begins to turn into a werewolf at night on her twelfth birthday. Shocked and wondering why she turned into a werewolf, she ran away from the orphanage and went out into the wild searching for answers, and her long-lost parents. Along the way, she meets some new animal friends, which she has the ability to communicate with in her werewolf form.

Full Synopsis
In an orphanage outside of a nearby forest, Reo, a girl whose parent's abandoned her after her birth, is about to celebrate her twelfth birthday, but the unnamed owners of the orphanage ruin it for her, making her run up to her bedroom. Later that night, she wakes up to find an orange tail has grown out of her, only a little bit later, she begins to fall on the floor, gasping for breath, she later begins to sprout fur around her body, her ears turn into wolf ears, and she grows a wolf nuzzle, following a howl afterwards.