From Shogakukan:
The time is the Taisho Era. Eventful young days of Aria who wants to become a pianist are portrayed in this saga of love, passion, and music.

From StarryHeaven:
The era is the Taisho period (1912-1926). Kaibara Aria, who wishes to become a pianist, takes the examination to become a preparatory student at the Tokyo School of Music. The passion in her playing overwhelms her surroundings, like a ripple on the surface of water. It was then that Aria had an encounter with the son of the Nishimikado noble family, Natsuo, and learns and shocking truth... The youth of the maiden blessed by the god of music in this stream of musical romance!