On one snowy night, Juri Kuran had a fight with her husband, Haruka Kuran, which led her to go to the Sakamaki's vampire soirée on her own. With all the anger she held in, Karlheinz attempted to comfort her, and they began to drink more and more together, until it led them to have a one night stand together. As a result, Juri ended up getting pregnant with Karl's child, and gave birth to a baby girl, whom she named Yumi Sakamaki. 17 years later, Karl brings the news to his children that for a period of three months, they will be attending Cross Academy's Night Class, along with the Mukami brothers after Ryoutei Academy was brought down by a natural disaster that hit the school. There, Yumi will find the truth about her mother.. and her birth.