Ryoichi is an ordinary uni student. During summer vacation, he comes to the amusement park "Hourai MAZE" with his friends. They come here for adventure! This "Hourai MAZE" used to be an amusement park but closed down due to strange phenomena and just ruins now. What they find is a huge meteorite flashing seven color lights. When they destroy this meteorite, an unexpected incident happens. "Time Travel". Where do they go? How do they come back? Ryoichi and his friends start a real adventure.