Tsubomi is a very sweet, but shy girl who is a massive fan of her classmate Mona Kawai. Tsubomi admires Mona for her sweet, cute image and charisma, but Mona is barely aware of her in return.
This changed when Mona developed the mistaken assumption that Tsubomi was a love rival for their classmate Kuroiwa Medaka. Mona felt threatened by this, not only because she might thwart her attempts to get closer to Medaka, but also because Tsubomi seemed to be just the sort of sweet, sincere girl that Mona pretended to be.
This misunderstanding didn’t last long however, as Mona soon discovered that Tsubomi was an admirer of hers, while Tsubomi learned of her crush on Medaka and vowed to help her get closer to him.
Later, she seems to lose her wingman role to Mona’s childhood friend Tomo.