You are being bullied every day, but you can't do anything about it. You have no one to talk to since you are an orphan and you need to work a part-time job every day to pay for everything. This leaves you with no time to study, and your grades are suffering. However, there is a girl in your class named "Yumi" who always supports you.

One day, while on the way back from school, you see Yumi walking across the street. Suddenly, a truck comes out of nowhere and is about to hit her. You rush to push her away, but you fail and both of you end up dead. However, you realize that you are not dead, and you are in a really strange place. Then, you see a beautiful woman with a halo above her head, and you realize that she is a goddess. You decide to ask her about Yumi, and she giggles. The goddess tells you that Yumi has been reincarnated into another world and will be chosen as the legendary hero to kill the demon king.

You then ask about yourself, but the goddess's face changes. She tells you that you weren't supposed to be there, and since you are already there, she has an idea. She decides to send you to this world as the demon king. Before you can say anything, you find yourself sitting on the throne. While you are still confused, you decide to explore around. When you leave the castle, you see a demon girl. She is shocked, and then she runs away. After a while, she comes back with two other demon girls.

The first demon girl: "Is that really the demon king...?"