Low on luck after a series of unfortunate events, You Keika works part-time to try to bring himself out of a life of poverty. After a strange encounter with a white-haired man in a junkyard, You wake up to discover that he was killed in a sudden accident and has become a spirit. The man he had encountered, Tanmoku Ki, is revealed as the 13th Youmeshi of the Tanmoki, the highest-ranking exorcist family of China. Noticing the wandering spirit, he offers You the opportunity to form a pact: he will offer You protection from humans, and in return, You will have to become his spirit shadow, keeping him safe and guarded at all times.
From then on, the two face untold challenges in the spiritual world, striving to keep those around them safe from harmful spirits. Along the way, the pact they formed grows into something more; a bond that neither of the two ever expected. Behind their roles as master and servant, a lingering admiration begins to emerge.