

After Ruby joins Aqours, she tells Hanamaru about the story of Rin and µ's, and Hanamaru finally decides to join Aqours, supporting Ruby in her endeavor. She talks Ruby's sister, Dia Kurosawa, into paying attention to what her sister actually wants, which was being a school idol. It is later revealed in Season 1 Episode 4 that Hanamaru actually was interested in school idols, especially after seeing a picture of Rin Hoshizora from µ's, but couldn't bring herself to being a school idol herself because of her appearance and lack of physical condition. Confused, Hanamaru quickly dismisses the invitation. In the anime, in the first episode, Hanamaru and Ruby are quickly approached by Chika Takami, who invites them to be school idols. Hanamaru has a distinctive verbal tic and dialect, tending to end her sentences with "zura" ( ずら, "zura"), as well as using "ora" as a first-person pronoun to refer to herself. She also attended the same kindergarten as Yoshiko Tsushima, also one of her friends.

Hanamaru is Ruby Kurosawa's best friend, and both are often seen near the other. She lives with her grandparents, and since she does not have a computer, she often reads a lot. Hanamaru, known as "Maru" for short (by herself and her friends), is a first year student and the daughter of a family who has run a nearby temple for generations.
