Kazuya Kinoshita is a college student who's girlfriend suddenly breaks up with him, leaving him heartbroken. Seeking to soothe the pain, he hires a rental girlfriend. His partner is Chizuru Mizuhara, who through her beauty, manages to gain Kazuya's affection.
But after reading similar experiences other customers had had with Chizuru, Kazuya believes her caring personality was all just an act to toy with him, and he rates her poorly. Aggravated, Chizuru lambastes him for his shameless hypocrisy, revealing her true pert self. This one-sided exchange is cut short, when Kazuya finds out that his grandmother has collapsed. They dash towards the hospital to find his grandmother in good condition. Baffled by Chizuru's presence, she asks who this girl might be. On impulse, Kazuya declares that they are lovers, forcing Chizuru to play the part. But with Kazuya still hung up on his previous relationship, how long can this difficult client and reluctant rental girlfriend keep up their act?
Jilted and heartbroken, 20-year-old Kinoshita Kazuya turns to Diamond, a Rent-A-Girlfriend app that leads him to a fateful encounter with Mizuhara Chizuru, one of the talents on offer.
Immediately after deciding not to rely on pretend dating anymore, Kazuya is hit with a triple whammy of reveals: Chizuru not only goes to his college but lives next door to him, and his grandmother is coming to visit and wants to see her.
Kazuya barely has time to deal with the fallout of the situation in the pub before the gang heads off on a short trip to Izu, where they run into someone unexpected.
Mami’s plan comes to a head as Kazuya decides to set the story straight, to mixed reactions.
The aftermath of the ferry incident signals a clear shift in Kazuya’s feelings. Meanwhile, there’s a conspiracy brewing at the hot springs inn he and his family decide to visit.
Having to spend a night in the same room with Chizuru sends Kazuya’s heart and mind racing. Meanwhile, Kuribayashi Shun has a surprise in store…
While Kazuya desperately tries to get Ruka to promise she won’t reveal his secret, she tells him her own.
Christmas rolls around with Kazuya not having met Chizuru for ages, and he sees something he never wanted to see.
Ruka is hellbent on knowing the full story behind Kazuya and Chizuru’s relationship, and once she does she decides to take action.
Kazuya learns that Kuribayashi's been down in the dumps and tries to figure out how he can help him.
On Chizuru's request, Kazuya goes on a practice date with Sumi, another rental girlfriend. Will he actually be able to help her and stay out of trouble while he's at it?
Chizuru and Mami go on an awkward rental date unaware that Kazuya has seen them together. How can Chizuru handle this situation?