About the Hells Is Dark with No Flowers Manga Volume 1 (Mature)

Seiji Tohno sometimes sees the people around him as monsters. It's a curse that has driven him to a life of despair…but all that changes one evening when he stumbles across a bewitchingly beautiful boy in a huge European mansion. The boy introduces himself as Shiroshi Saijou, and before he knows it, Seiji has agreed to become Shiroshi's part-time assistant. It turns out that Shiroshi's 'proxy service' is to consign yokai-possessed sinners to Hell, which will bring Seiji face-to-face with an unimaginable host of horrors!