On October 17, 1948, Frederic Chopin, one of the most influential composers for the piano, succumbed to sickness and died at the young age of 39. Three hours prior to that, in the world according to this RPG, Chopin saw a dream of a fairy-tale land populated by people with incurable diseases but also magical powers.

Eternal Sonata takes place in this dream world. Chopin comes into contact with Polka, a young girl who resides with her mother in the village of Tenuto. Polka is near her death, and Chopin, Polka, and her young friend Allegretto as they look for some way to make use of Polka's great powers to help save her. It's a whimsical fantasy, but this RPG designed by developer tri-Crescendo also a complex and combo-based battle system of swords and magic weaponry. In keeping with inspiration, music and story play a big part in Eternal Sonata. Performing the piano numbers that Chopin left to the world is Russian pianist Stanislav Bunin, with musical composition by noted game composer Motoi Sakuraba.