Keonma Diaoh
Koenma is the son of Enma Daioh, the ruler of the Spirit World. When his father is away, he all responsibilities fall to him. Koenma mostly does the paperwork and gives orders to the Spirit World detective. The closest person to him should be George, who is his servant, but he isn't always nice to George. Koenma tends to take his frustration out on him. Koenma's powers are in his trademark pacifier. Actually, that pacifier gathers his spirit energy and can be used as a powerful seal to capture dangerous and strong Demons.  A funny note: Koenma always changes his looks when he goes to the Living World  because he doesn't want people to make fun of him. He transforms into a very nice looking young man, but always keeps the pacifier. Koenma is actually hundreds of years old, but he looks like a 4-year-old kid.Sometimes Koenma doesn't just look like a kid, he can act like one too. especially towards Ogre. But as the series progresses, Koenma seems to become more serious. In the Sensui saga, we learn about his feelings of guilt towards Sensui. After all, Koenma gave him the orders for the mission that changed Sensui's whole life.