"Shiryou Jutsushi nado Kegarawashii" to Shokei Sareta node, Mazoku ni Tenshin Itashimasu

A duke's daughter and the crown prince's fiancée... I, Rachel Sheringham, was both and wielded dark attribute magic, which allowed me to use necromancy. I was accused of colluding with demons due to it and was executed. With regret as my source of power, I will return to life as a lich!!!