The daughter of a boss went out for a spring outing. When she came back, she was racing with her best friend. Because someone in front of her couldn't brake quickly, she got into a car accident. After that, she traveled to a country that had never been seen in history. And I happened to live in a martial arts family with parents and three older brothers who loved me. The queen, who had just gone out to explore the world, was killed because of the Hongmen incident ten years ago. She also unexpectedly discovered that even her best friends in modern times had also traveled through time. Let's see how we three sisters can solve the Hongmen incident ten years ago. What kind of big secret is behind this? Will it be revealed?