Koenma

King Enma Jr., usually addressed as Koenma (コエンマ, "little Enma"), a combination of Ko (meaning child) and his father's name, is the son of spirit realm ruler Enma, and the one who takes responsibility of his father's work when he's away. Koenma rebels against his father when he discovers that his father has ordered Yusuke's execution because Yusuke is a Mazoku. Koenma usually appears as a toddler with a pacifier in his mouth, though he's at least 700 years old. This pacifier is Koenma's trademark wherein it is where his powers are stored. The pacifier gathers his pure Reiki and can be used as a powerful seal to capture dangerous and strong Youkai. This seal is called "Evil Sealing Ring" or the "Mafuukan". Koenma's main abilities are based around this pacifier, which holds spirit energy used for barriers, sealings, and bringing life back to corpses. The closest person to him should be George (A blue ogre), who is his servant, but he isn't always nice to George. Koenma tends to take his frustration out on him. Koenma has wisdom of the universe and its history, and will help however he can, though at times he's cowardly and a typical comic relief character. He can transform himself into his adult form of a bishōnen, yet has claimed during the Yokai tournaments that he prefers maneuvering in his baby form.

Source: Wikipedia