As the Spirit Detective of Earth, Yusuke Urameshi and his friends fight many fantastical battles against demons and even humans to protect the world from certain doom. Overseeing all the events of Yu Yu Hakusho is Koenma, ruler of the Spirit World and the godly being who helped Yusuke come back to life after his untimely death in the series premiere.
Source：https://www.cbr.com/yu-yu-hakusho-koenma-pacifier-mafuuken-powers-explained/
