Mami Nanami presents herself publicly as a sweet, friendly, and approachable individual. However, beneath this polished exterior lies a more manipulative and possessive nature, especially when it comes to matters involving Kazuya Kinoshita and Chizuru Ichinose. She has demonstrated tendencies that suggest a sociopathic streak engaging in calculated, conniving, and sometimes petty behavior. When her façade slips, Mami’s jealousy and possessiveness become apparent, often unsettling those around her.

Although she is no longer in a relationship with Kazuya, Mami continues to involve herself in his life, frequently seeking information about him and the girls around him. She actively tries to interfere in his relationships, though it remains unclear whether her actions stem from lingering feelings or pure resentment.

From Kazuya’s perspective, Mami sometimes appears caring and empathetic, occasionally voicing concern over his reliance on rental girlfriends. However, her private remarks and actions suggest otherwise. In secret, she has expressed disgust toward Kazuya’s relationship with Chizuru and is determined to break them up. On several occasions, she has manipulated Kazuya’s emotions such as kissing him or inviting him to meet privately despite being aware he was already in a relationship (though initially unaware that Chizuru was a rental girlfriend).

In the spin-off series Kanojo, Hitomishirimasu, Mami is further portrayed as a “maneater”, a woman skilled in seduction and manipulation. She uses her charm with calculated precision, particularly around men, reinforcing her image as someone who hides her true intentions behind a disarming smile.

Mami Nanami is a petite young woman with bright blue eyes and shoulder-length blonde hair styled in a voluminous bob, accented with soft pink highlights at the tips. She has a slender build and is often noted for her attractive legs and delicate figure.

Her fashion sense is casual and trendy, often consisting of light, seasonally appropriate outfits that include skirts and purses highlighting her fair complexion and stylish flair. While her daily outfits vary, she consistently presents herself in a way that draws attention.

Mami is aware of her physical attractiveness and occasionally uses it to her advantage, particularly when dealing with men. However, she becomes visibly self-conscious when comparing herself to women with more prominent figures, such as Chizuru Ichinose.

Despite her sweet and inviting appearance, Mami is capable of adopting a cold and intimidating presence when angered or frustrated. In these moments, her sharp demeanor has been known to scare off potential suitors and even leave her friends stunned by her sudden change in attitude.

Mami Nanami revealed that she briefly dated two boys during high school, though both relationships ended quickly. During her first year at Nerima University, she began dating Kazuya Kinoshita. Early in their relationship, Mami admitted that neither of them had much romantic experience, joking that they were “sailing in the same leaky boat.” However, without much warning, she ended the relationship, stating that she liked someone “new.” Following the breakup, she blocked Kazuya on Twitter but maintained a friendly front when they encountered each other on campus.

At a drinking party, Mami was surprised and irritated to find Kazuya accompanied by an attractive girl Chizuru Mizuhara, whom he introduced as his girlfriend. Growing suspicious and curious, Mami later invited Kazuya and their friends on a beach trip, where she subtly referenced a conversation they once had about potential baby names. Later, she followed him to a nearby store and was surprised to see Chizuru with him. Back at the beach, she lured Kazuya away behind the rocks and kissed him, prompting Kazuya to abruptly announce a breakup with Chizuru. This angered Kibe, who accused Mami of manipulating Kazuya’s emotions and punched him. Mami denied any wrongdoing.

Still intrigued, Mami invited Kazuya to a private outing at a pool. However, their plans were interrupted when Kazuya jumped into the ocean to rescue Chizuru during a separate incident. Afterward, Mami ignored Kazuya’s attempts to explain, further escalating the tension between them.

Later, Mami saw Kazuya walking with another girl Sumi Sakurasawa and introduced herself, causing discomfort for Kazuya. As Sumi clung to him affectionately, Mami appeared surprised by his apparent popularity with women. She vowed not to inform Chizuru, but secretly looked into Sumi and discovered her occupation as a rental girlfriend.

Not long after, Mami learned of Chizuru’s real identity and booked her for a rental session. While initially teasing, she quickly shifted to harshly criticizing Chizuru’s relationship with Kazuya. When Chizuru asked Mami if she still had feelings for him, Mami became visibly agitated and defensively told her to mind her own business before leaving.

Mami later confronted Kazuya on campus, letting him know she was aware that both Chizuru and Sumi were rental girlfriends. She advised him to stop relying on rental services and pursue a real relationship instead.

One evening, Mami unexpectedly visited Kazuya’s apartment. Since Chizuru was inside at the time against agency rules she and Kazuya panicked and hid. Mami briefly entered the apartment, oblivious to their presence, and left. However, while walking away, she recalled seeing a purse in the room, triggering suspicion.

Mami continued investigating, eventually appearing at Kazuya’s part-time job, a location she previously visited with Chizuru. She invited him to speak privately, drawing suspicion from Ruka Sarashina, who intervened. When Mami questioned Ruka about her relationship with Kazuya, Ruka confidently declared herself his girlfriend. Mami criticized her for continuing the relationship after their breakup, but Ruka dismissed the concerns, saying their relationship was casual. Although Mami appeared calm, she was internally frustrated. Her mood soured until she coincidentally encountered Chizuru at a train station and noticed the same purse from Kazuya’s apartment. Through subtle questioning, she deduced that Chizuru was still seeing Kazuya and had been inside his home.

Later, Mami was shown using a computer to search for information on Ruka but found nothing substantial. However, she discovered that Kazuya’s family owned a well-known liquor store and used that information to contact Nagomi Kinoshita, Kazuya’s grandmother.

Some time afterward, Kibe visited Nagomi to discuss matters related to their website and was surprised to find Mami already speaking with her, having apparently familiarized herself with the Kinoshita family business.

Eventually, Mami confronted Chizuru again on campus, confirming her suspicion that Chizuru was indeed the same person working as a rental girlfriend. Mami agreed to keep Chizuru’s secret on the condition of an undisclosed agreement.

The given name Mami (麻美) is composed of the kanji ma (麻), meaning “hemp” or “flax,” and mi (美), meaning “beautiful.”

Her surname Nanami (七海) combines nana (七), meaning “seven,” and mi (海), meaning “sea” or “ocean.”