The story tells about an ordinary college student named Yuhi Amamiya. One day, a talking lizard announced that he was chosen as a knight to save the world. Just when Yuhi was half-believing, he was attacked by the enemy and was saved by the princess Asahina Satsuki, whom he was supposed to protect. Unexpectedly, the princess turned out to be a demon king who wanted to conquer the world. Yuhi was attracted by Satsuki's spirit and strength and became her loyal knight.