Momoko, Kaeru no Uta ga Kikoeru yo.

Riki and Momoko are twins, the brother, Riki, a strong, healthy third grade Primary School Student, while Momoko has various mental and physical handicaps and goes to a special handicapped children's school.

Always complaining that she too wanted to go to proper school, she would often throw tantrums, but settle down when she hears Riki sing the "Chorus of the Frogs", her favourite song.

Soon, Momoko is is given permission to attend Riki's school once a week, as a part of a exchange learning program.

There, she cheers Riki on during a Physical Education class, and this lead to Riki's team winning.

However, a member of the losing team, Ryuji, insults Momoko about her intelligence.

Riki, angered beyond restraint, hits Ryuji, and is subsequently punished by the principal and parents.

April.

Riki's class is now in fourth Grade, but the hostility of Ryuji towards Momoko continues.

However, the other members of the class become friends with Momoko, drawn to her happy personality.

One day, Momoko's condition suddenly becomes worse, and is carried to hospital.

Meanwhile, Riki, Ryuji and some others are chosen to run in the relay of the athletics carnival.

Though Riki plans to encourage Momoko by winning the relay, the fastest runner, Ryuji, claimed that If Riki is running, then he would not...