The film unfolds within a high-rise residential building in Roppongi, Japan, where eight anonymous individuals—four men and four women—pay to enter an anonymous sex club. As the night begins, the club's owner briefly addresses the guests, informing them that they have from midnight until 5:00 A.M. to engage in any sexual activities they desire. A set of rules is established: guests must shower after sex and use the restroom, condoms are mandatory, and men are required to respect the wishes of the women.
Once the owner exits, a palpable silence falls over the group as they make the most of their time in this intimate yet ambiguous setting. Following the departure of the clerk/bartender to fetch snacks, the men and women gradually begin to engage in small talk, allowing connections to form. It is the Freeter, played by Hirofumi Arai, who makes the first move by inviting the Office Lady, portrayed by Yoko Mitsuya, to venture downstairs. As the night progresses, the remaining participants pair off: the Salaried Man [Kenichi Takitoh] forms a connection with the Child Care Teacher [Eriko Nakamura], the NEET [Sosuke Ikematsu] connects with the University Student [Mugi Kadowaki], and the Factory Worker [Ryusuke Komakine] finds himself with the Regular Customer [Muck Akazawa].
As the interactions unfold, the initially timid college student reveals an unexpectedly fervent side, coupled with the revelation that the factory worker is still a virgin. After their initial encounters downstairs, the atmosphere becomes looser, allowing for deeper conversations. The clerk eventually returns with an array of sex toys, adding an element of spontaneity to the night. During this newfound openness, the Salaried Man confesses to cheating on his wife, while the Child Care Teacher admits to having had fantasies involving one of her students.
As partners begin to alternate, the NEET and University Student develop an attraction that transcends mere physical desire. On the contrary, the Factory Worker and the Regular Customer remain paired, feeling neglected by the others. After several more encounters, the Freeter expresses desire for the college student, prompting the NEET to feel possessive, which leads to a confrontation where he admits, “I don’t love her.” Ultimately, he yields, allowing the others to pursue their pairings freely. The night takes a turn when a couple—comprised of the Couple Woman [You Nobue] and Couple Man [Tokio Emoto]—joins the rest of the participants in the living room, turning the atmosphere tense once more.
Encouraged by her boyfriend, the couple woman decides to pair up with the NEET, while the couple man opts for the university student. A scene ensues where both the college student and the NEET cast glances at each other during their separate encounters, hinting at their growing bond. Frustration simmers within the couple man as he discovers his girlfriend’s enjoyment during the encounter, igniting tension between them, leading to their eventual exit.
As the night continues to unfold, pairings shift once more, culminating in a reconnection between the NEET and university student. After returning upstairs, they gather again, only to be drawn back downstairs by loud noises. The group cheers when they discover the Factory Worker and the Regular Customer finishing up, with the customer exclaiming that she has just had the best sexual experience of her life, much to the delight of the factory worker.
As the clock approaches 5 A.M., the clerk opens the blinds, flooding the room with a harsh light, which prompts the women to shyly put their clothes on while the men dress silently. A mishap occurs when the college student loses her phone, leading the clerk to use the NEET's phone to retrieve her number—an act that brings unintended consequences. The owner then explains that the men must allow the women 15 minutes to leave before they can exit themselves, aimed at preventing stalking. The regular customer’s relationship with the owner comes to light amid this final rush.
After leaving the club, the NEET receives a text from the college student, inviting him to meet at a café. To his surprise, she asks him to delete her number, insisting that her actions from the night were not reflective of her true self, and that they should not meet again. The story concludes with the college student resuming her life at school, surrounded by friends, while the clerk cleans up the club, receiving a joyful photograph of his newborn baby, encapsulating the night's myriad of experiences and emotions.
