Aileen Lauren Dautriche's life changes forever on the day her engagement with the crown prince Cedric Jeanne Elmir is nullified so he can be together with Lilia Rainworth. The event triggers Aileen's memories from her past life—she has been reincarnated in an otome game as the villainess, who is destined to die in the final act. To prevent her predetermined demise, Aileen has only one option: to court the game's last boss, Claude Jeanne Elmir—the proclaimed "Demon King" and Cedric's half-brother—and marry him. However, it is easier said than done, as Claude distrusts her intentions. Instead of giving up, Aileen adamantly tries to win his heart by helping Claude fulfill his wish: to build peace between humankind and demonic beasts. But time is running out, and it is up to Aileen to change the course of not only her tragic ending but Claude's as well.

Kurotori Chiyoko, a 5th-grader in elementary school, loves the occult. One day, a friend requests her to do a love fortune-telling. Chiyoko tries to summon Cupid, but thanks to a stuffy nose, accidentally summons a witch named Gyubid instead! From that day on, Chiyoko starts learning witchcraft from Gyubid, the self-proclaimed hottest instructor of the magic world. The training regimen is tough, and punishment for slacking is harsh. Fortunately, Chiyoko is able to keep her extra-curricular studies secret, aided by the fact that no one else can see Gyubid.

Higepiyo is a little chick with a mustache, who is seeking to aquire masculinity with his friend Hiroshi but ends up being entangled with a skin of heated milk.

Hiroko Matsukata is a woman who works for a magazine company. She puts all she has into her work, and is known as a strong, straight-forward working girl, who can at will turn herself into Hataraki man (working man) mode. Despite Hiroko's success at work, her life lacks romance. Even though a hard worker, she'd leave early anytime to go on a date. Too bad her boyfriend is even bigger a workaholic than Hiroko.