Boy Awakens Ancient Curse After Witnessing his Girlfriend's Death

Anime Recap Summary: Yuta, a joyful boy, shares a close bond with his friend Rika. On his birthday, Rika gives him a ring, symbolizing their promise to marry and be together forever. Though Yuta doesn't understand the concept of marriage, he is happy with the idea of being with Rika indefinitely. However, tragedy strikes when Rika has a fatal accident. To Yuta's horror, she comes back to life as a monstrous entity, driven to fulfill their earlier promise.