Reiji Kikukawa, who has a strong sense of justice, graduated from the police academy with the lowest score ever. He becomes a police constable, but is suddenly fired by the Police Chief due to "disciplinary" issues. In actuality, the firing is part of a carefully orchestrated plan to set him up as an undercover cop in the Yakuza.

Nodame and Chiaki mutually decide that it would be for the best if they parted ways for a while so Nodame can practice for an upcoming competition. However, when things don’t go her way, she gets impatient and depressed. While Nodame is away, Chiaki’s former pianist Rui Son returns to take her place. To make matters worse, Rui and Chiaki are set to play the song Nodame dreams of playing with Chiaki herself: Ravel’s “Concerto in G Minor”.

Arima Kousei won numerous piano competitions while under the strict watch of his mother. He was known as the human metronome during that time. Since the death of his mother, Kousei has been unable to hear the sound of his piano. He then meets Miyazono Kaori through childhood friend Sawabe Tsubaki. Kaori plays the violin and has a free sprit. Since meeting her, Kousei is able to face the piano again. Meanwhile, Kaori holds a secret.