One of the children of Myoue and Koto. He is human, unlike his siblings. After his parents left the City Through the Looking Glass, he became one of the council of three and earned himself the title of Myoue, after his father. In present day, he takes care of and watches over Koto and her brothers.

Yakushimaru was a normal kid whose family was wiped out. The monk Myoue had found his dead body and resurrected him with enchanted pomegranate that made him immortal. Since then Yakushimaru sought for a way to die.