Y

One of K's friends and fellow peers. He was once a great magician capable of even rising the dead who succumbed to greed and power. When he began to be ostracized and feared by the people he created a love potion so they would love him but that made things worse when humans began to fight over him. Rather than give up his power he went to the desert to be alone. To his horror, the love potion caused the sun itself to fall in love with him and caused the sun to move closer to earth, eventually to crush earth. However, Jin's brother found him first and showed him to hide himself from the sun in exchange for Y becoming his third pupil. Y is usually covered in bandages and is often mistaken for being an old man. Because of his fondness and worry for D he asks K to transfer his magic and knowledge to D, leaving him a normal human. Though he's killed during his effort to save D he's resurrected by the spell he transferred to D. It's revealed in volume 6 that he and D got married. *From Wikipedia*