Uragirareta Touzoku, Kaitou Maou ni Natte Sekai wo Shouaku Suru

Keith, a thief, has his family taken prisoner and is forced into a party to defeat the Demon King. Thanks to his efforts, he manages to defeat the Demon King, but he is betrayed and nearly killed by the King and heroes, who are not happy with Keith. Keith barely escapes with his life, but before he