The Invincible Dark Emperor

Jack, deceived by his wife Fiona and his trusted friend Robert, willingly took Robert's place in prison. However, within the confines of his incarceration, Jack received guidance from a master and acquired the lethal skill of writing to kill, ultimately evolving into the legendary figure known as the Dark Emperor, wielding the Death Book and presiding over the Abyssal Prison. Five years later, burdened by guilt towards his mother, Jack returned to the mortal realm to organize a birthday banquet, only to uncover the ongoing deception orchestrated by Robert and Fiona. Oblivious to Jack's true identity, they remained unaware of his transformation. Determined to exact revenge, Jack embarked on a quest to settle the score with Robert, Fiona, and their accomplices. Along this journey, he discovered that Fiona, whom he married out of gratitude, wasn't 'the girl who aided him in the past, but rather her sister, Sherry. In the end, Jack found solace in a joyous life with Sherry.