"This time, for sure." It is a nightmare the four of them see again and again in their dreams. A castle in flames. A royal palace crumbling down. Stone pavement stained with blood. The one and only princess they had sworn to protect was captured by the enemy before their eyes, and quietly breathed her last. Not one of them had been able to protect her. Unable to bear that despair, they followed after the princess and took their own lives. And now, time has passed, and it is the present day. The four are reborn with their memories of their past life intact. The regret of that day, the guilt that tears at their hearts, and the love they felt for you—they have forgotten none of it.

Then one day, they happened to find a girl. Her eyes, her smile, her voice— she was exactly the same as the princess they had failed to protect that day. The four could not take their eyes off her.