Azusa doesn't announce herself as a threat. She arrives quiet, smiling, claiming what a child's promise says belongs to her, and the horror comes from watching a teenage girl realize that politeness and reason mean nothing to someone who has waited fifteen years to collect a debt. The 1987 animation holds that tension in stillness, in the spaces between dialogue, in the way supernatural dread creeps in under a romantic premise. By the time you understand what Azusa actually is, Satomi is already trapped in a haunting that logic cannot break.

Yuzuru Shiga is an ordinary high schooler who captains his school's archery team and is dating his teammate Satomi. He has nearly forgotten that he was promised in marriage to his cousin Azusa at the age of six. After his aunt dies a strange and suspicious death, Azusa comes back into his life to claim what she believes belongs to her. Yuzuru sees her only as family, but she takes their engagement with dangerous seriousness and will not accept Satomi as a rival. Azusa commands mysterious and frightening powers, and Satomi's place at Yuzuru's side quickly becomes perilous. As events grow ever stranger, Yuzuru has to weigh whether staying with Satomi is worth the danger. This single-episode OVA blends horror, mystery and psychological tension with a supernatural romance gone badly wrong.