Love in Hell. Volume 3 - Reiji Suzumaru

IF HELPING OTHER HURTS YOU...IS IT A SIN?
Senkawa Rintaro has been in Hell for a while now, and settled into a routine: get tortured, earn money, and help his adorable demon overseer get a complete makeover. Yes, even in Hell, there is goodness to be found.
Just look at the shy girl who gives Rintaro a bunch of money! Too bad that results in her losing her head...literally. Rintaro doesn't even know her name, but he's determined to pay her back, even if it means breaking the rules and getting paid to run errands for demons. Whether it's picking life-sucking flowers in the desert or scaling great heights, Rintaro's on a mission that will earn him something even better than money: answers about why he's in Hell in the first place!