Memoru is one of 245 survivors who arrived on Earth from the Riruru Star after their ship made an emergency crash-landing. Her people are so small that they can easily stand on a human's palm. One day, drawn by beautiful music, Memoru follows the sound and discovers a large house she’s never seen before. Inside, she finds a girl taller than her playing the piano.
Memoru returns to the house in secret, accompanied by her friends Popitu, Rupangu, and Pi. However, the human girl, Marielle, appears gravely ill, close to death. Moved by pity, Memoru's tear falls onto Marielle's lips. Miraculously, the girl begins to recover, and a deep, lasting friendship begins to blossom between them.