Konyaku Haki made no Tookakan

Arrogant and selfish, the notorious daughter of an earl, Elena Boulder, lost her memory in a freak accident shortly after her fiancé, Viscount Oscar West, called off their engagement. "It would seem that Elena has no redeeming qualities." "...I feel conflicted that you yourself are sympathizing with me." Oscar becomes attracted to Elena, who seems like an entirely different person from before, but their engagement has already been called off. These are the last 10 days that she, who has completely accepted their parting, and he, who now doesn't want to let go, will be engaged. (Source: Kadokawa, translated)