My Demon Lord Ascension

Overcome with an incurable illness stemming from the curse of a “Hero”, Demon Lord Baal commences the “Demon Lord Ascension”: a legendary event in which the next Demon Lord will be crowned. It is a competition between the relatives of the Demon Lord, where even death is permitted.
It is an illustrious throne to have, as the land of demons sits at the pinnacle of technological advancement, melding the traditional medieval ways of the world alongside cybernetic development.
Receiving news of this, exiled prince and son of ill Demon Lord, Merlin, relishes the opportunity, bringing his human companions with him to his homeland to enter the Demon Lord Ascension.
Though he is hardly welcome, as he is seen as the “black sheep”--an outcast–among his family. Against all odds, with spite fueling him, Merlin seeks to take the Demon Lord crown for himself with his Dreaming Grimoire System to aid him–but first, he must go through his family.

I hope you can find something to enjoy in 'My Demon Lord Ascension'--whether it be the high-octane action, power system, or familial struggled!