High school studen Mafu lost her mother when she was a child and lives with her father, step-mother and six-year-old half-sister Maaya. Her drunken father beats her and she feels isolated at school, and her only companion is little Maaya with her vivid fantasy life. One day, Mafu and Maaya get lost in the woods and meet Masa and his uncle Jiro, who live in an old house at the forest entrance and make a living as hunters. As she spends time with Masa, Mafu recalls songs from her childhood and memories of her mother. Mafu and Maaya embark on new a journey in this mysterious forest overflowing with music and song.

女子高生のマーフは、幼い時に母を亡くし、実父と義母、そのこどもである６歳のまあやと暮らしている。しかし酒に溺れる父には乱暴に扱われ学校でも孤独な生活を送っていた。夢見がちな幼いまあやとだけはいつも一緒にいる。ある日、森に迷いこんだマーフたちは、狩猟を生業とし、森の入り口に建つ古びた一軒家に住むマサとその叔父の次郎に出会う。マサと過ごす日々に、亡くなった母親の記憶やなつかしいうたを思い出すマーフ。音楽とうたのあふれるふしぎな森から、こどもたちの新たな旅がはじまる。