Xia Sen, an ordinary high school student with yin and yang eyes, is silent, gentle, unsociable, and has a weak sense of existence. Because he was born with the ability of "seeing", he was ostracized by the people around him. In the summer of 18 years old, in the dim sunset, Xia Sen met the non-human being who changed his life - the God of Death.
The powerful, beautiful and flamboyant Hell Messenger transformed into a little black cat, and together with the boy he watched the joys and sorrows of the human world and the ghost world one after another.
If life is destined to end here, if we are destined to have unequal time, please don't forget the red line you put on the boy's wrist in the early summer forest.
Remember me, this is the best promise you can give me.