Sonoda Lucky is one of septuplets who love the piano. However, after a divorce, Lucky was left with only his mother while his father took his siblings. They became the prodigies known as the "Otogami Sextuplet Pianists", while Lucky was forced to live an abusive life in a relative's home after his mother fell into a coma. When his mother wakes up, he believes everything is right with the world, until he discovers she only has one year to live. Lucky decides to become a professional pianist so his mother can see him perform with his siblings.