Natsu Kasyu

Airi is a graduate student with a degree in the study of folklore. As part of her research, she decided to go to a small village with a group of friends, to investigate local legends. She does not know that the people worshiped the Slit-Mouthed woman as a living god, and intend to use her and her friends as a human sacrifice. In the end, Airi is injured and decides to fight, becoming a Slit-Mouth hunter.”

退屈な日常から抜け出したい女子高生のアミは、家庭教師で大学生のヒロキのサークルの飲み会に参加する。酔っ払ったアミは1次会でヒロキになぜか強引に帰されるものの、駅のホームのベンチで不覚にも眠ってしまう。そのころ、ヒロキのサークル仲間たちは1人の女の子を泥酔させたあげく、集団レイプしようと画策していた。