I recommend One Piece: Death's Vice-Captain and One Piece: The Strongest Death. These two books are derived doujinshi novels from One Piece and Death. The story of the protagonist, Chen Qi, transmigrated to the world of One Piece and obtained the Death God System. On the other hand,"The Strongest Death from One Piece" was the adventure of the protagonist, Ming Wang, in the three worlds of Death, Naruto, and One Piece. I hope you like this fairy's recommendation. Muah ~π