Mami Nanami, a central figure with intricate layers, attended Nerima University and briefly dated Kazuya Kinoshita during their freshman year. After one month, she abruptly severed ties, citing interest in someone "new," then blocked Kazuya across all platforms—triggering his reliance on rental girlfriend services.

Externally, she projects friendliness with a petite frame, blonde bob featuring subtle pink highlights, bright blue eyes, and light skirts or outfits accentuating her fair complexion. This charming veneer shatters when agitated, revealing a cold, intimidating aura that unsettles others.

Her core traits include possessiveness, jealousy, and manipulation. Upon discovering Kazuya with Chizuru Mizuhara—introduced as his girlfriend—Mami grew suspicious and sabotaged their bond. She lured Kazuya to the beach, manipulated him into kissing her, and provoked a public "breakup" with Chizuru. Later, she rented Chizuru to confront her, condemning their arrangement as a "loveless fake relationship" and demanding Chizuru quit rental work.

This behavior roots in trauma: raised under strict paternal control, she endured an arranged marriage plan for social advancement. Her high school romance ended when her father coerced her boyfriend into leaving, cementing her belief that all love is "make-believe" and fueling chronic distrust.

Mami extended her schemes beyond Kazuya and Chizuru, investigating his ties to Sumi Sakurasawa and Ruka Sarashina. After deducing Sumi was a rental girlfriend, she confronted Kazuya under false concern, urging him to seek authentic love. She also intruded on Kazuya’s apartment, spotted Chizuru’s purse, and later confirmed Chizuru’s presence via a train encounter.

Her tactics escalated when she researched Kazuya’s family, uncovering their liquor store. She ingratiated herself with his grandmother Nagomi Kinoshita, leveraging this to infiltrate their family. Ongoing interactions with Nagomi and Kazuya’s friend Kibe underscore her persistent disruption of his life.

The spin-off *Kanojo, Hitomishirimasu* frames her as a "maneater," adept at calculated manipulation of men through charm—aligning with her broader use of allure for control.

Despite her antagonism, glimpses suggest unresolved feelings for Kazuya. She reminisced about shared moments like naming hypothetical children and bristled when questioned about her motives. Her warning to Chizuru—that Kazuya cannot find real love while using rentals—hints at conflicted concern.

Ultimately, Mami’s actions stem from envy and trauma. She wields manipulation to cope with insecurities and relationship disillusionment, relentlessly controlling Kazuya’s romantic entanglements while masking vulnerabilities behind a crafted persona.