Mao

摩緒

Born in the late Heian era, Mao claims to be at least 900 years old by the mid-1920s. Orphaned as a child, he scavenged for food and dwelled in a cave system, navigating the darkness by scent, sound, and the faint winds blowing through it. Coincidentally, this cave navigation served as a trial to join a school teaching onmyodo, a Chinese mystical art blending early science with the supernatural. Mao outperformed the other pupils hoping to enter the school, saving the life of a young Shiranui in the process. Soon, Mao found himself learning a vocation and gradually improving his circumstances in the late 1100s.
Mao's skills, however, were average compared to many of his fellow students. Consequently, it was a shock when he was named the intended successor to the school by their master. Mao was infatuated with the master's daughter, Sana, and her hand in marriage was promised to him along with knowledge of the most esoteric and important teachings, particularly the life-lengthening skill so many sought to master. All of this was a ruse, however, as Mao was intended to be used as a ritual sacrifice; his modest skills made him an unimportant figure easily killed for the greater good.
However, Byoki, a cat demon created by the school, soon escaped and rampaged throughout the temple, murdering dozens until Mao faced off against it. With his blade in hand, Mao managed to decapitate the cat creature, though he accidentally merged with Byoki's body, gaining more power in the process. The disembodied head of Byoki fled, and Mao has no memory of what happened next. However, the survivors of the school insist he murdered Sana, the woman he loved. Mao has lived for 900 years with this burden, quietly living a simple life as a doctor treating yokai and humans alike. It is not until 1922, during the Great Kanto Earthquake, that he next encounters Byoki in a battle that rips time and brings him into contact with Nanoka, a girl from the modern day who was pulled into the 1920s.