In the near future when technology has significantly advanced, a famous AI TV fortune teller seemingly foresees high school student Asahi Kashiwagi's day with pinpoint accuracy. On his way to school, he encounters Aoi Izumisawa, Bai Mongfa, Karin Istel, Amelia Irving, and Ilya Ilyukhin. Despite meeting them for the first time, Asahi suddenly receives love confessions from all of them at the end of the same day, perfectly aligning with the fortune teller's prediction. As if that was not enough, Asahi soon learns that these five individuals are actually candidates to become his bride, and they have been invited by his father to live at Asahi's home. Left with no other choice, he reluctantly allows them to stay, resulting in a bawdy turn of events that brightens up his average high school life. However, as Asahi spends more time with them, forgotten memories gradually resurface. While uncovering the hidden truth, Asahi begins to believe that his fate with these potential partners might be more than just mere coincidence.

Third-year high school student Jirou Yakuin is in love with his childhood friend and classmate, Shiori Sakurazaka. Thus, he hopes to be paired with her for the marriage practical: their school's practice of randomly selecting boy-girl pairs to live as pretend married couples while monitoring and rating them on how close they have gotten. Meanwhile, the lively Akari Watanabe wants to be assigned to her crush, the popular and good-looking Minami Tenjin. Much to their dismay, Jirou and Akari find out that not only have they been paired together, but so have Shiori and Minami! Determined to be with their crushes, Jirou and Akari strive to earn as many points as possible, as the top 10 pairs earn the right to switch their partners—so long as both couples agree.

Following a prank pulled by his perverse friends, Junichi Hashiba asks a gal out in an attempt to change the fact that he's a hopeless virgin. Yukana Yame, the girl in question, is disgusted by Junichi's groveling. However, through a series of teasing remarks, she soon finds herself bonding with him and ultimately accepting Junichi's confession, much to his surprise. Hajimete no Gal follows Junichi as he overcomes his lack of self-confidence and suppresses his sexual urges, all while thrust into a whole new school life full of lively girls and unpredictable mayhem.

After socially awkward technology specialist Manabu "Gaku" Taira is saved from thugs by the outgoing Haru Tennouji, the two men find that they get along with each other well. Years later, Gaku, who is having a tough time getting a job due to his timidness, is convinced by Haru to apply for a position alongside him at Dragon Bank, one of Japan's largest IT companies. During their interviews, the company's board director, Kirika Kokuryuu, takes an interest in Haru and Gaku's contrasting personalities. However, Gaku does not get hired by the company, leading Haru to quit the job on his first day in protest. Nevertheless, they decide to embark on an ambitious plan of making a trillion dollars. In order for their scheme to come to fruition, Haru and Gaku start looking for potential investors, but everyone rejects their extravagant idea. In spite of that, the two soon find themselves getting an offer from Kirika—and with her investment, they might just be able to reach their goal.