Fia Ruud, the youngest member of the Ruud family, discovers she's the reincarnation of a powerful "Great Saint" and must keep it secret as she pursues her dream of becoming a knight.

After being publicly betrayed by the crown prince and thrown into prison, noblewoman Elizabeth escapes her kingdom with the legendary Seven Grimoires. With help from a viscount from a neighboring nation, she rebuilds her life while plotting revenge against the kingdom that cast her aside.

Seven years after humanity was devastated by a major disaster, a beacon of science and prosperity rises in Kamitsubaki City. But lurking in its shadows are Tesseractor monsters born from human darkness. Only the Witchling, five girls with Song of Purification, stand against them. With every note, they fight, not just to protect the peace of the city, but to heal a broken world.

Student council president Takane Takamine is a popular star student. On the other hand, Koushi Shirota doesn't have many friends. That all changes when Koushi accidentally discovers Takane's ability to go back in time and alter past actions just by changing her lingerie. After some pestering, Koushi agrees to help Takane and be her closet, by having spare lingerie on hand.