Manga Fukushuu O Koinegau Saikyou Yuusha Wa, Yami No Chikara De Senmetsu Musou Suru

It would seem that he should be carried and adored by absolutely everyone, because he is the same hero who destroyed the sinister demon king. This is exactly what Raoul thought after the final battle. However, he was betrayed by the princess and the aristocrats, who killed his family and all those dear and important to him, after which they executed him too, concocting a false deed. But before he died, his heart was filled with darkness.
He vowed to take revenge on his enemies, tear them to pieces, revel in their blood and dust them. He was going to make them endure suffering at times worse than they brought him. At that moment, he gained the power of darkness and was reborn. With a sneer, he rose again, wanting revenge on everyone.
Meanwhile, in the city, people began to prepare for the parade, which was to be held that day. They did not yet know what tragedy it would end with.