There is no system, no mission, and a sudden time and space ability descends on the foursome. They can step into any historical scene that is a foregone conclusion and become real ordinary people in the event. In the copy, they can work hard to rewrite the tragic ending, but once they return to reality, everything remains the same. There is no ambiguity or romance, just pure support between companions. Experience disasters and turbulence, face the cruel past, see human nature clearly, sharpen your mind, and slowly find your own answers through immersive historical experiences.
Purpose: The general trend of history cannot be tampered with, and individual goodwill still has value. Even if countless people are saved and local disasters are reversed in the dungeon, the real timeline will always remain the same. All the running and redemption will not rewrite the established historical facts, but can redeem oneself traveling through history.