Karin

Race: Demon
Role: Demon Queen

The Demon Queen who ruled the country and was sealed away 1,000 years ago by a "hero".

Despite this, she seems to hold no ill will towards humanity. In fact, she seems to like them quite a bit, and is eager to hear their stories. During the time she ruled the area, she introduced many cultural and technological innovations from the Demon World, like the concept of insurance, and the game of Chess. She is fond of books and games, and is constantly asking Kazuto to buy her more.

Her power is sealed by six Seal Stones that are buried throughout the mountain. At first, she appears as a phantom, barely able to interact with the world. As more of the stones are recovered, she regains her physical form, and eventually her full power. She doesn't want any lives to be lost for the sake of her revival, even if they see her as an enemy.

Spoiler

While it is told that she was a tyrant who took over the country, the truth is that she was friends with the human queen who was the previous ruler. The queen willingly passed on the throne to Karin, who took it to help her friend. The human queen and her husband took on ordinary lives. However, their child was unsatisfied with such a life and felt that they deserved the throne that was their birthright. They sealed Karin away, and vilified her, leading them to be known as a "hero".