One day, a peaceful countryside town is suddenly attacked by a giant robot. To protect the Earth, boys and girls board robots to fight. Soundbacks are robots transformed by stones called "Kanade," which absorb real-world sounds. Their forms change according to the sounds, with different sounds like knocks or wind chimes offered each episode, leading to a differently shaped robot appearing every time. There was a secret: after the battles end, the "Kanade" lose their power and revert to mere stones, but the offered sounds and the memories associated with them are gradually taken away from the heroine, Towako...