The main character meets a girl called Kaguya drifts to a peaceful island Windalia. She lost all her memories and affections. The main character reaches out to the "heart" of many people and charges the energy to take back the "heart" Kaguya has lost. Open the "key of heart" appeared from Kaguya will spread the world you can explore. What happens when Kaguya takes back all of her memories and affections? A sorrowful but heartwarming story now begins.