During a beach getaway with her pals, Hana, the most adorable girl in school, is embroiled in a supernatural occurrence labeled the "Red Night Eve." A gargantuan, transformed shark sets its sights on Hana as she takes a swim. Happily, she is saved by Yayako and Yuuto Kagimori, siblings from her school who are well-versed in these incidents and even have an AI support program called Acacia on their tablet to assist them. Soon after, Hana and the Kagimori siblings are thrust into another event, this time with her beloved class pet parakeet undergoing a monstrous transformation. With all these supernatural happenings, Hana's life will never be the same again!
