Rentarou Aijou has it all: looks, intelligence, athletic skill, and popularity with peers and mentors alike. Unfortunately, none of these qualities help Rentarou with his love life. On the day of his middle school graduation, he is once again turned down by a girl he confesses to, earning his one-hundredth rejection in a row. Down on his luck, he goes to a matchmaking shrine and wishes to finally get a girlfriend in high school. When the god of the shrine suddenly appears before him, Rentarou is told he will meet an astronomical total of one hundred soulmates in high school. Though Rentarou initially does not take this foretelling seriously, his doubts disappear when, on the first day of school, he meets two of these soulmates—Hakari Hanazono and Karane Inda—who both confess to him. With fated encounters and love confessions galore, Rentarou's life is about to get a lot more exciting.

When the "Sirens," an alien force with an arsenal far surpassing the limits of current technology, suddenly appeared, a divided humanity stood in complete solidarity for the first time. Four countries—Eagle Union, Royal Navy, Sakura Empire, and Iron Blood—formed Azur Lane, paving the way for the improvement of modern warfare, which led to an initial victory against the common threat. However, this tenuous union was threatened by opposing ideals, dividing the alliance into two. Sakura Empire and Iron Blood broke away and formed the Red Axis, and humanity became fragmented once again. As a seasoned and experienced fighter, the "Grey Ghost" Enterprise shoulders Azur Lane's hope for ending the war. But behind her stoic persona hides a frail girl, afraid of the ocean. Even so, she continues to fight as she believes that it's the only purpose for her existence. Meanwhile, Javelin, Laffey, and Unicorn—three ships from the union—stumble upon Ayanami, a spy from the Red Axis. Strange as it may seem, they try to befriend her, but as enemies, their efforts are for naught. Still, they persevere in hopes of succeeding one day. Amidst the neverending conflict within humankind, the keys that could unite a fragmented race might exist: a soldier coming to terms with her mysterious personality and camaraderie between those with different ideals.

In the year 2062, Earth finds itself fiercely battling Artemis—an AI which rebelled against humankind following a grand-scale workforce automation project failure years prior. In the hope of winning the war, a group of three highly skilled human warriors is assembled, known as the guardians of humanity. Empress, the last surviving guardian, wakes up alone in an empty research facility. Unable to recall anything from the past except a place called "Lighthouse No. 8," she begins to search for answers. It is not long before she discovers an impending threat from Artemis—and she is the sole person who can save the world from destruction.

Fuutarou Uesugi's efforts as the Nakano quintuplets' private tutor are finally paying off. The academic performances of the five sisters are steadily improving, and they are each closer than ever to achieving their respective dreams. However, it appears that Fuutarou has become more than a teacher for the girls, who urge him to sort out his feelings. The undecided young man promises to make a decision by the end of the school festival. However, Fuutarou's task will not be easy, as the Nakano sisters pull out all the stops to win his heart before it is too late.