Murasaki arrives as an agent from Facultas Academy, tasked with retrieving their top graduate, Nice, who departed before completing his studies. Holding the academy's second-highest historical scores, Murasaki nurses a quiet bitterness toward Nice, who consistently eclipsed him academically despite never formally graduating. This fuels his persistent drive to surpass Nice and earn his acknowledgment through direct competition.

After completing his mission, Murasaki defects from Facultas upon discovering the academy deceived him into facilitating Shizuku's capture for unethical purposes. He joins Nice’s detective agency, Hamatora, becoming his primary investigative partner. Their professional dynamic thrives on frequent bickering, yet Murasaki demonstrates unwavering loyalty, repeatedly prioritizing Nice’s safety over his own in perilous situations. They share living quarters, with Murasaki typically shouldering daily chores and cooking.

Murasaki exhibits a logical, calm, and collected personality, tackling tasks efficiently. He displays irritation when others undermine his dignity or make ill-considered decisions. Though generally reserved, he maintains positive relationships with colleagues, including Hajime, whom he initially distrusted but later accepts despite her eccentricities. His pragmatic outlook prioritizes the financial viability of job requests, contrasting sharply with Nice’s focus on case substance.

His Minimum ability activates upon removing his glasses, granting superhuman physical strength and body hardening. Manga adaptations call this the "All or Nothing Minimum," while the anime refers to it as "Gravity Minimum." Extended exposure to Hajime’s Nihilist Minimum later causes severe physical deterioration, weakening his body, limiting his power usage, and often resulting in pain. This condition persists until the finale of Re: Hamatora, when Nice utilizes Skill’s transplanted Ego Minimum to restore Murasaki’s ability.

In Re: Hamatora, Murasaki confronts Art during Art's leadership of Freemum but is overpowered, sustaining injuries that further compromise his already weakened Minimum. He survives and rejoins the group, temporarily unable to utilize his power effectively until its full restoration. Across all media, including the super-deformed Mini Hama: Minimum Hamatora, his core traits and narrative arc remain consistent, emphasizing his evolution from rival agent to dedicated partner within Hamatora.