I´m the Villainess, So I´m Taming the Final Boss, Vol. 3 LN

A brazen attack on the demon king has left him without his memories or his formidable magic. Vulnerable and unaware of the many pitfalls that surround him, Claude has even forgotten his engagement to Aileen, the villainess who reincarnated into the world of her favorite game. With Lilia and other conspirators maneuvering to take advantage of the crown prince’s sudden bout of weakness, Aileen has no choice but to steal Claude’s heart once again and foil anyone who would do her beloved harm!