When a person who under goes extreme depression/anxiety loses control, they will become a demon consumed by darkness. Luckily there are those devoted to hunting these demons. Kagami Kenichi was taking a shortcut home from school until he gets attacked by a demon. A girl named Miyu appears and fights off the demon with her gun. Kagami's normal life comes to an end as he ends up making a contract with Miyu by kissing her, causing his soul to become her source of power and her gun to get bigger and stronger. Kagami soon comes to realize that humans actually turning into demons is real!
(Source: MU)

The office of the Time Eliminator offers a unique service, the ability to eliminate an event that happened in the past. Rex, the man with the power to travel through time, may look young, but he's a professional. He goes back in time well-prepared, with various gadgets and even an earpiece for communication with his support in the present. While Rex typically takes on cases for profit, he's also particularly looking for ones that might give him a chance to obtain a magical "Babylon Item".

The first case of the series is from the last remaining descendant of Fred Abberline, who was one of the detectives who failed to solve the notorious Jack the Ripper murders. Ever since then, the Abberline family has been cursed. Could the curse be the sign of someone in the past using a Babylon Item?! It's up to Rex to go back in time to the Jack the Ripper incidents and find a way to remove the curse from the Abberline family!