Shounen Sarutobi Sasuke - Movie

In medieval Japan, a boy named Sasuke and his sister live in a forest along with several young animals of different species. One day, one of the animals is grabbed by an eagle and thrown into a lake. Sasuke and another animal jump into the lake to save it. But a monstrous salamander arrives and devours one of the animals. Sasuke tries to fight the monster, but is defeated. And the beast leaves the lake, revealing its true form: a female demon named Yakusha. Sasuke's sister tells him Yakusha was transformed into a salamander by a powerful wizard millennia ago. But now she could muster enough power to have her normal shape back. And now she will found a reign of terror in Japan! Then, Sasuke decides to seek a magician master to learn to fight against Yakusha to save Japan and avenge the death of his pet.