Ukei Kaito, also known as the Second Chance Avenger and previously known as the Next Demon Lord, is the titular protagonist and the anti-hero/anti-villain of the light novel and manga series
The Hero Laughs While Walking the Path of Vengeance a Second Time. He was originally a 17-year-old ordinary Japanese high school student who was summoned to another world as a hero. However, in the original timeline, after killing the Demon Lord, he was betrayed and killed by Princess Alessia and her soldiers due to Alessia's manipulations when they painted him as Next Demon Lord. Until the Earth Goddess revives him and the dead in a second timeline, and he is summoned to take revenge on Alessia and those who wronged him, determined to return to Japan.
He is the leader of his party called the Avengers, declared by Alessia as the "Evil Adventuring Party".