Noblesse Gambit: Fukushuu Reijou wa Odoru, Hanzaikyou to no Danzai Yuugi

The Seven Heroes and the absolute queen Phobia, with their fairytale-like power, defeated the Demon King and brought lasting peace to the world. However, behind the scenes, they harbored wicked and ruthless natures, and Adel, a noblewoman's daughter, had everything—her family and everything else—taken from her. Standing on the brink of death, she pleaded in a fit of rage: she would beg them to pay with blood. Appearing to answer her wish was a rare genius known as "the Professor"... "If you seek a blade worthy of that murderous intent, I shall specially instruct you." A fierce and magnificent tale of revenge between a young girl and a lord of crime begins.

(Source: Kadokawa, translated)