Toshiaki Nakamura operates as a supporting character with shoulder-length violet hair styled in a half-ponytail, loose bangs framing the right side of his face, and one distinctive upward-protruding strand. His violet eyes mirror his hair color. This hairstyle occasionally garners attention, exemplified when classmate Miyuki compliments its beauty during an interaction involving a gifted pink hair accessory.

As a student, Nakamura shares a close friendship with protagonist Ryo Sakaguchi but consistently fails to grasp or endorse Sakaguchi's fervent obsession with boys' love media. He questions Sakaguchi's persistent BL-focused discussions and occasionally voices bewilderment regarding Sakaguchi's actual sexual orientation. Nakamura displays a reserved, observant demeanor, often countering Sakaguchi's emotional outbursts with stoic reactions like raised eyebrows.

His interactions extend to other characters: he forms an acquaintanceship with Rumi Nishihara through Sakaguchi, exhibits visible discomfort around Yuujirou Shiratori—particularly when Shiratori invades his personal space—and maintains neutrality toward Shiratori's friend Akira Ueda.

Episodic situations place Nakamura in circumstances misinterpreted through Sakaguchi's BL lens. Instances include unintended train gropings due to Nakamura's hair being mistaken for a woman's, sparking public misunderstandings that Sakaguchi spins into BL fantasies. These recurring patterns frame Nakamura's reactions within BL-inspired humor, contrasting his own disinterest or unease.

Nakamura's documented role centers on high school experiences, functioning as a grounded counterpoint to the central cast's eccentricities, especially Sakaguchi's BL-centric worldview.