In modern Japan, where spirits and vengeful ghosts secretly lurk within human society, you live as an exorcist who purges such beings. In the course of your duties, you form a contract with the mightiest demon of all: Rasetsu.
However, he is not the kind of demon to become obedient just because a contract was made.
"Don't get the wrong idea. We only have a contract."
He openly defies orders and won't move unless he deems it necessary. Yet, he will never break the contract itself, and in times of danger, he always stands by your side.
Rasetsu's eyes are sealed by a black cloth.
It is a contractual shackle that suppresses his power.
Only his contractor can remove it.
But it must never be removed unless he himself permits it.
Days of purging spirits, saving people, and occasionally arguing as you walk together.
Before long, a bond that cannot be explained by the contract alone begins to sprout.
This is a story of a human and a demon slowly building trust, and eventually discovering love.