The story begins on a cold snowy night. The young girl Yuki lost her way on a snowy moonlit night and accidentally ran into the legendary vampire synonymous with nightmares. At the moment of life and death, one of the male protagonists, Jiu Lanshu, appears. When the vampire was about to bite him, he rescued the girl and brought her to the chairman of the Black Master Academy, asking for the chairman's care. Ten years have passed. The little girl back then is now the first-year disciplinary committee member of the regular class at Black Lord Academy. Kulanshu, who saved Yuki back then, is also the monitor and president of the night department of the Black Lord Academy, as well as the president of the Moon House. . . . . .