The Entertaining Demon

Thomas Sakaki was an ordinary child with a nice life, until one day he was kidnapped by unknown assailants with six other kids. All of them were forced to participate in "The Lost Incident Project", which involved dueling an AI and if they got anything wrong then they would get punished. Six months later, the kids were rescued from the program and returned to their lives. Everything from "The Lost Incident" was just a fleeting memory for Thomas, with nothing but Hanoi's involvement seared within his mind. Thomas has made it his mission to get vengeance on Hanoi. Year's later, he's created a persona to take on Hanoi and meets someone from his past with a similar goal.