In a parallel world where Serena exists, Kirika, Shirabe, and Maria, all three Visited Nastassja's research facility.
Suddenly, a mysterious man attacked the research facility, And Kirika, Shirabe, Maria, and Serena, all four, tried to stop him. Three fell to the mysterious man’s attack, and only Kirika escaped.
The mysterious man disappeared from the research facility, And Shirabe, Maria, and Serena began to suffer from an unknown illness.
According to Nastassja’s research, The mysterious man was actually a vampire, And the three girls were suffering from a vampire’s curse.
The only way to save them would be to defeat the vampire.
Without a moment’s delay, In order to save three precious sisters, One girl went after the vampire.