Set in Edo-period Japan, the story revolves around O-Ei, the talented and outspoken daughter of the renowned artist Tetsuzo, who is better known as Hokusai. Despite Tetsuzo's fame, he leads a humble and somewhat chaotic life, working amidst clutter and overlooking his familial responsibilities. O-Ei, who inherits her father's artistic skills, assists him in completing his artwork while also striving to develop her own unique style. She frequently navigates the bustling streets of Edo, balancing her dedication to art with the challenges imposed by her family dynamics, particularly concerning her younger sister O-Nao, who suffers from blindness.

As O-Ei matures both as an artist and an individual, she forms friendships and encounters various individuals that influence her worldview. The narrative explores themes of artistic passion, familial duty, and personal growth against the backdrop of a rapidly changing society. Through her journey, O-Ei grapples with her identity and the expectations placed upon her by her father's legacy, all while seeking validation for her own artistic contributions. The interactions between characters reveal the complexities of human relationships and the sacrifices entailed in the pursuit of art.