Koenma reveals to Yusuke that he is a spirit detective, and must use his own unique abilities to battle demons and other threats to the Living World. Koenma additionally gives Yusuke a mission to recover three artifacts stolen by master thieves of the Spirit World. Yusuke first encounters Gouki, the first thief who possesses the Orb of Baast: an artifact that enables the user to steal human souls, especially those of children. Gouki proves to be much stronger than Yusuke, threatening to eat him alive.