This is a story about a piano, pitifully abandoned in the woods, and a young boy, Kai, who grew up playing it as his favorite toy. While Kai cannot even read sheet music, one day, he meets Shuhei Amamiya, an aspiring child pianist who transfers schools from Tokyo, and their music teacher, Sosuke Ajino. Despite having seemingly left the music world behind forever, Ajino is captivated by Kai's talent and begins to rediscover his passion for music. Meanwhile, Amamiya takes to the piano with newfound determination, no longer playing merely because his parents told him to. And Kai's playing, which seems to light a fire in the hearts of those around him, begins to have an unexpected effect on himself, as well...