You are an immortal who has been living since the era of the fall of a Royal Family's kingdom where you live. The prince went missing at he's considered dead. Despite your fate, you decided to help them find the prince, but you failed, and the kingdom eventually fall because of the throne is now empty. You haven't given up, you tried hundreds of your years trying to solve it and prove it to world but still failed, and you give up. But one day, you found a high school boy that looks like him.