The protagonist, Kagami Tamae, is an office worker who sleeps a little better than other people. Also known as 『Kyūkei-san』
When she woke up after suddenly fell asleep in a chair, she saw a strange screen.
『Please input your level』
Just for fun, she typed in「9k」which means 9000.
When the enter button was clicked, it was …… what a surprise to see that she was reincarnated directly into another world.
Her appearance is so blue with a pair of horns, she has turned into the strongest demon lord with a human heart, making her confused, however, she was lucky enough to meet some girls by chance and became friends with them, and today she is continuing to make more friends as an ally of humanity.