Kazuya Kinoshita is portrayed as an indecisive and emotionally driven young man with notably low self-esteem. His lack of confidence often leads him to compulsively lie in order to avoid confrontation or discomfort, even when doing so complicates his situation further. He frequently struggles to tell the truth and tends to act irrationally, often jumping to conclusions and failing to stand up for himself when necessary.

To avoid the consequences of his lies, Kazuya typically extends falsehoods rather than confront the truth. A notable example is his prolonged fake relationship with Chizuru Ichinose, which he maintains to cheer up his grandmother. Despite the complications that arise, he continues the ruse out of a desire to protect others’ feelings and avoid causing emotional distress to those around him.

Beneath his cowardice and frequent dishonesty, however, Kazuya is ultimately a kind-hearted and selfless person. He has demonstrated genuine courage in moments of danger and remarkable self-control when faced with temptation. He is also highly supportive of others and often puts their needs ahead of his own.

Kazuya’s greatest strength is his unwavering optimism. While he tends to be pessimistic about himself due to his insecurities, he approaches tasks with persistence and determination when motivated. His close friend Kibe once remarked on Kazuya’s relentless optimism and expressed admiration for it. Despite his immaturity in many areas, Kazuya is shown to be naturally good with children, impressing both his mother and Chizuru with how easily he bonds with them.

In Chapter 107, Kazuya showcases a more mature and capable side of himself while organizing a crowdfunding campaign to support Chizuru. Applying his studies in Business Administration, he demonstrates strong analytical and planning skills accurately calculating equipment costs, salaries, and script payments. He also researches past campaigns to refine his own strategy, proving that, when motivated, he possesses significant potential as a businessman.

Additionally, Kazuya has a deep interest in marine life. He frequently visits aquariums and possesses extensive knowledge about aquatic animals. In Chapter 93, during a trip to Aqua Park Shinagawa with Sumi Sakurasawa, he shares trivia about manta rays and sawfish, highlighting his genuine passion for marine wildlife.

Kazuya Kinoshita is a young man of average height with a plain and unremarkable appearance. He has messy, spiky light brown hair and dull brown eyes, contributing to his overall modest and forgettable look.

His typical outfit consists of an orange T-shirt featuring a black spiral design at the center, worn over a long-sleeved black shirt. He is often seen wearing either striped pants or jeans, reflecting a casual and somewhat understated fashion sense.

Kazuya Kinoshita began his college life on a high note, confident in his future, with a girlfriend, Mami Nanami, and a generous allowance of one million yen. However, his optimism was quickly shattered when Mami abruptly broke up with him, stating that she had met someone else. Heartbroken and emotionally distraught, Kazuya discovered an app called Diamond, a rental girlfriend service, and impulsively booked a date with the most highly rated girl: Chizuru Mizuhara.

Their first date went smoothly, but after reading online reviews and realizing Chizuru maintained the same affectionate demeanor with other clients, Kazuya felt deceived. Frustrated, he left a one-star review and rented her again, intending to confront her. During their second meeting, he accused her of being fake, to which Chizuru sharply responded, defending her profession and scolding him for misunderstanding the purpose of the service.

Their argument was cut short when Kazuya received news that his grandmother, Nagomi Kinoshita, had collapsed. Chizuru accompanied him to the hospital, where his family assumed she was his girlfriend. Embarrassed and unable to explain the truth, Kazuya claimed they were dating. Although reluctant, Chizuru went along with the lie. Afterward, they agreed to maintain the deception for the sake of his grandmother’s happiness, with a plan to “break up” gradually.

The following day, Kazuya encountered Chizuru on campus dressed in a modest, unassuming style. Surprised to learn she also attended his university and lived in the same apartment building they agreed to keep their professional relationship secret. During another hospital visit, Chizuru discovered her own grandmother, Sayuri Ichinose, was in the same facility and had become friends with Nagomi. Pressured by circumstance, Chizuru also lied, claiming Kazuya was her boyfriend to avoid revealing her work as a rental girlfriend.

Later, Kazuya ran into his friends Kibe and Kuribayashi while walking with Chizuru. To protect his image and out of concern for Nagomi’s close friendship with Kibe, he once again claimed that Chizuru was his girlfriend. Although frustrated, Chizuru supported the lie, and the group went out for drinks. There, they unexpectedly encountered Mami Nanami.

While Mami pretended to be friendly, she secretly resolved to sabotage Kazuya and Chizuru’s relationship, believing it to be genuine. She subtly insulted Kazuya during the gathering, prompting Chizuru to walk out, unable to tolerate Mami’s behavior. Later that night, a drunken Kazuya was approached by Mami, who tried to rekindle a connection. However, Kazuya declined and chose to speak with Chizuru instead. During their conversation, Chizuru apologized and advised Kazuya to seek closure with Mami to move on from their past and end the charade between them.

After Nagomi was discharged from the hospital, she insisted on visiting Kazuya at his apartment and expected to see Chizuru as well. In a panic, Kazuya asked Chizuru for help once more. Initially absent, Chizuru arrived just in time and cooked for the family, winning Nagomi’s favor and softening her suspicions.

Shortly after, Kazuya was invited on a beach trip, where Mami was also in attendance. Unbeknownst to him, Chizuru happened to be at the same beach with her friends. When Mami began questioning Kazuya’s relationship with Chizuru, Chizuru intervened in her rental girlfriend persona. Kazuya contemplated ending the fake relationship but was confronted by Kibe, who believing the relationship was real scolded and physically reprimanded him. Chizuru praised Kazuya for enduring the situation, unaware she was running a fever.

That evening, Chizuru and Kazuya rode a cruiser, attempting to relax. Mid-ride, Kazuya received a call from Mami asking to meet at the pool. Just as he considered going, he overheard people reporting that a girl had fallen overboard matching Chizuru’s description. He immediately jumped into the water to rescue her, dropping his phone in the process. Though he managed to save her, he nearly drowned from exhaustion. Chizuru successfully revived him. Afterward, the two returned home separately, and Mami chose to cut ties with Kazuya. At home, Kazuya attempted to distract himself with thoughts of Mami but found his feelings for Chizuru interfering, marking a shift in his emotional focus.

During a family trip organized by Nagomi, Kazuya informed Chizuru that he wouldn’t be able to visit Sayuri. Coincidentally, Sayuri was staying at the same hotel, and Chizuru was accompanying her. To their surprise, Kazuya and Chizuru were assigned to the same room, resulting in an awkward situation particularly when Kazuya accidentally walked in on Chizuru post-shower.

Though initially upset, Chizuru agreed they were trapped in the situation and suggested confronting their grandmothers. However, circumstances prevented them from speaking out, and they ultimately spent the night in the same room, maintaining the façade of their relationship.

The given name Kazuya (和也) is composed of the kanji kazu (和), meaning “harmony” or “peace,” and ya (也), meaning “to be” or “also.”

His surname, Kinoshita (木下), combines ki (木), meaning “tree” or “wood,” and shita (下), meaning “under” or “below.” While likely coincidental, some fans have interpreted the surname as a tongue-in-cheek reference to certain personal habits depicted in the series.