In a world where humans and beastkin coexist, a young swordswoman named Belle Lablac journeys across the land with her talking sword. As the last remaining human in a world that has forsaken humanity, Belle travels from town to town, helping those in need while searching for answers about her own existence. Along the way, she encounters various characters who challenge her worldview and help her uncover the truth about the mysterious disappearance of humans from this world.