Raizen

The strongest of the Three Kings, the God of War, and the strongest character in the series. Raizen, however, was injured in battle and nursed back to life by a human who he fell in love with and impregnated with his baby. Raizen vowed to never eat another human again until he saw her again, though she died before he could, and, keeping his promise, went on starving himself for hundreds of years, and his power decreased as his hunger grew. The family line of the witch doctor continued into Yusuke Urameshi. Just minutes before starving to death, Raizen still had enough strength to fight evenly with S-Class warriors. Raizen possessed Yusuke during his battle with Sensui, and with Raizen's help Yusuke defeated Sensui. Raizen then tells Yusuke to train relentlessly for months so he will surpass Raizen and gain his kingdom before he dies, but Raizen dies before Yusuke surpasses him, Yusuke still gains Raizen's kingdom.