A powerful vampire causes chaos in Japan. Yukina, an apprentice Sword Shaman, encounters Akatsuki Kojou, the Fourth Primeval.

Yuzu and her friends met and discuss relationships, which Yuzu intends to have one when she gets transferred to the new school. The next day, she preps her up for her first day of school. Unknowingly, she is attending an all-girls school with a strict dress code. The student council spotted Yuzu and bickered with other council members until their President, Mei, confronts and gropes her to confiscate her smartphone. Yuzu tries to get along with her classmates but to no avail, until Harumi helps her and tells about the rules of the school. As she explores the campus grounds, she sees Mei and their teacher Amamiya sharing a kiss, to which she frantically flees. After school, a stressed out Yuzu goes home and sees her mother. As they discuss Yuzu's stepfather, her mother introduces Mei as her little stepsister. Yuzu is trying to converse with Mei but the latter continuously ignores her, until she brings up of what she had seen kissing with their teacher. Mei suddenly approaches Yuzu and kisses her, telling how it feels like to be kissed.