Hatarake! Suima-san

"Humans in this country don't take sleep seriously enough." This is a story about work -- that is, an office worker in her late twenties and her sleep demon, whose job it is to get her to sleep! Yoko is a hard worker, that's for sure. She's missed her last train home yet again and feels herself losing the battle to sleep in the bathroom. That's when she senses a shadow over her shoulder. She turns around only to find -- a sleep demon?! "Oh. You can see me." says Nero, a regular old office worker at Sleep Demons Incorporated in the Underworld. His monthly salary comes from getting humans go to sleep, and from today, he's in charge of Yoko. Thus begins Yoko and Nero's daily quest to improve her quality of sleep -- for both of their sakes! (Source: MangaPlaza) Note: Includes an extra chapter.