About

The setting is China. In a corner of the underworld, Yen and Guest run an "odd-job shop" that takes on any request. In this world, there are rare individuals born with a "Mark" somewhere on their bodies. Each Mark harbors a different power, and few know of their existence. Among them, the "Black Mark" is extremely rare and has long been considered a symbol of heresy and taboo. And Guest is a bearer of that Black Mark. "Mark-Bearers" Individuals born very rarely among humans who possess non-human powers. A "Mark" appears somewhere on their body from birth. Abilities differ depending on the shape, color, and position of the Mark, and even if the position is the same, the specific nature varies by individual. Mark-Bearers are very rare and almost unknown in general society. On the other hand, they are famous enough in the underworld that people say, "Never anger a Mark-Bearer." "The Black Mark" Normally, Marks have different colors for each person. However, the rare "Black" is considered exceptional and has been feared since ancient times as a symbol of heresy and taboo. In particular, those with a Black Mark on their tongue are called "Devourers," who consume and exorcise all impurities. Few know of their existence, and some in the underworld become wary just by seeing a Black Mark.