Jigoku no Ashita

Ashita, a high school student who is head over heels in love, falls down a flight of stairs in shock after a heartbreak. When he wakes up, he finds himself in the arms of a beautiful woman on a boat headed to the afterlife. Ashita is gently comforted by the beautiful woman, named Gasha, and takes a tour of Hell at her request; soon after he ends up enrolling in demon school, where Gasha is the headmaster. Thrown into the midst of demons who are too loyal to their desires, a school life that inevitably leads to bloodshed begins!

(Kodansha, translated)