The alien Abyssal Fleet continues to threaten humanity, and the Kanmusu—girls endowed with the spirits of Japanese warships—are mankind's last hope. With their ongoing struggles, the Kanmusu are almost certain to sink below the waves into their demise. The Mutsuki-class destroyer Kisaragi is one of the unfortunate ships to meet such a fate. However, following a successful night raid, the Eighth Fleet's Kanmusu spot Kisaragi alive but unconscious, floating to the sea surface. But the anomalous situation and Kisaragi's strange behavior leave Kanmusu cautious of her. Furthermore, the other ships start to hear mysterious voices and come across crimson waters that damage their equipment. Strangely, Fubuki, the lead ship of the Fubuki-class destroyers, appears unaffected. As Fubuki and the other Kanmusu tackle the unusual occurrences around them, the harsh reality of their existence and the Abyssal Fleet begins to unravel. Even so, the girls must keep facing forward to liberate the sea and protect those they cherish the most.

On the vivid and glistening waters of the Kanda River, Jetters and their respective Shooters race together on their jet skis, speeding through the wind as they participate in Jet Races—the world's most intense aquatic sport! Chasing her dream of becoming a professional Jet Racer like her mother, Rin Namiki transfers to Asakusa Girls' High School in Tokyo. There, she stumbles upon Misa Aoi, a first-year student like her. However, tensions arise when Rin and Misa find themselves competing in a race against Team Dress from the prestigious Musashino Girls' High School. As a result of the race, Rin tries to join her school's Jet Racing club, only to discover that there is none. But, her resolve is unshaken, and she decides to recruit Misa and three other girls to create her very own team: Kandagawa Jet Girls. With her heart set on winning the annual Kandagawa Cup, Rin, alongside her team, approaches the grandest stage of them all.

In visual novels, an imaginary flag is defined as an event that serves as a turning point for the whole story. A player triggering the romance flag for a heroine will proceed to her route, or a death flag will signify that a certain character will die afterwards. High school student Souta Hatate can see these flags above a person's head, and has the ability to bring them down to stop certain events from happening. Using this power, he has prevented other people's deaths. But, after a past accident with him as a sole survivor, he ended up believing that only misfortune will befall those who are near him, and has refrained from making friends or having relationships ever since. However, everything starts to change after transferring to a new school. After toppling another death flag, his classmate Nanami Knight Bladefield notices his powers and tries to learn more about him, promising that she will remain at his side no matter what may happen. Thus begins Souta's journey as he meets new friends and acquaintances while uncovering the mysteries of his ability—which might run deeper than what anyone expects.

A year after they met, Kazuya Kinoshita and Chizuru Mizuhara still regularly see each other through the rental girlfriend app. However, Chizuru confesses that she is ready to quit her job to pursue her true passion—acting. Despite wishing to maintain the relationship they have, Kazuya decides to support her dream. When Kazuya goes to watch Chizuru's anticipated first play, he is amazed by her talent and ability to captivate the audience. At the same time, he is saddened at the thought that she will undoubtedly be scouted by the famous director in attendance. However, after the show, Chizuru explains that the director recruited another actress, lamenting her lack of talent. Frustrated on her behalf, Kazuya resolves to rent her every week to help her financially. But as Kazuya's ex-girlfriend Mami Nanami lingers around for unknown reasons, hesitance muddles his true feelings, and fulfilling his promise to Chizuru becomes uncertain.