The World's Peerless Poison Magic User (Poisoned to Death)

My coming-of-age celebration is suicide by poison. In the Eduar family, which values magical talent above all else, Rondo, who has no aptitude for magic, was a disgrace to the family and had no right to live. As he lamented his powerlessness and drank the poison, he acquired the world's only 'poison magic' and narrowly escaped death. However, Rondo is surrounded by enemies. To survive, what will he do...?!