Manga by author Kiama Kiichi - Status ongoing

An alternate world (isekai) school gag manga. The manga follows Yamada, a company employee who is around 30, and a young demon king.

Mitsuya-san is one of the few long-lived demi-humans in Japan. She is not very familiar with modern life, so in order to relearn, she became a high school student at the age of (approximately) 200 years old!With her race's unique beautiful appearance and her warm and soothing personality, she grabs everyone's hearts in this high school comedy!