Suzu, a shy high schooler in rural Kochi who stopped singing after her mother drowned saving a child, signs into U, an online world of five billion users where each person takes on an avatar built from their biometrics. As her freckled avatar Belle, she finds the voice she lost and becomes a global singing sensation. When a feared figure called the Dragon crashes one of her concerts and the network turns against him, Suzu sets out to learn who he really is.