Ten years ago, at the peak of the VRMMO development industry, a game titled "Kiwame Quest" entered the scene with potential like no other. Boasting a colossal total of 10 sexdecillion branches of possible story scenarios, this game pursued ultimate realism, ranging from humanlike NPCs to the perfect replication of all senses and physical abilities. But it soon became apparent that the game was too realistic, and the popularity of VRMMOs in general gradually began to plunge. At present, due to an accident a few years prior, the high school student Hiroshi Yuuki now immerses himself in full-dive RPGs as a form of escapism. After failing to acquire the latest version of his favorite game, Hiroshi stumbles upon a game shop and meets its beautiful clerk Reona Kisaragi who convinces him to buy a copy of Kiwame Quest so that they can play together. The first time Hiroshi plays the game, he marvels at the realism it offers. However, his astonishment is short-lived as he sets off a series of misfortunes, quickly realizing that the game is even worse than his already stressful life. Nevertheless, Hiroshi still finds himself logging on again despite his growing contempt for the game. With no do-overs in his current disadvantageous situation, Hiroshi only has one goal—clearing the game!

As a young boy, Prince Oscar Lyeth Increatos Loz Farsas was cursed by the Witch of Silence, rendering it all but impossible for any woman to bear him a child. After 15 years of fruitlessly seeking a way to lift the spell, Oscar resorts to enlisting the help of a different witch. To this end, he heads to the Azure Tower, home of the Witch of the Azure Moon. Ascending the tower is no easy task; for decades, no one has overcome the array of traps, puzzles, and enemies designed to repulse any challengers. Oscar, however, easily climbs to the top, where he meets the fabled witch, Tinasha. To the prince's surprise, despite being hundreds of years old, Tinasha looks like a beautiful young woman in her late teens. Oscar explains his circumstances to the witch, who quickly perceives the true nature of his affliction. Though she claims that undoing the spell would be tremendously difficult, Tinasha proposes a workaround—to find Oscar a partner capable of withstanding the curse's effects. Realizing that such a woman is right in front of his eyes, Oscar boldly tells the witch to marry him. Though he is promptly rejected, the young prince refuses to back down, and the two eventually reach an agreement: Tinasha will leave the tower and live with Oscar for the next year. As the two continue searching for a way to lift Oscar's curse, word of Tinasha's emergence from isolation spreads, catching the attention of all sorts of old acquaintances.

Professional wrestler Genzou Shibata sports the body of a mountain, but beneath his hulking appearance is a man with an extreme affection for animals. Facing off his opponents in the ring as the legendary "Animal Mask," Genzou wins the hearts of crowds everywhere with his iconic tiger persona. During the bout for the title of World Champion against his greatest rival, the Macadamian Ogre, Genzou is suddenly summoned to a fantasy world by a princess. With her kingdom being threatened by a monster infestation, she pleads the wrestler for assistance—to which he answers by knocking her out with a German suplex! Escaping the castle and finding himself stranded in a mysterious land, Genzou decides to begin his career as a beast hunter to capture and befriend creatures far and wide. Joined by the wolf-girl Shigure, the dragon-girl Hanako, and the vampire Carmilla Vanstein, the professional wrestler pursues all kinds of dangerous requests for the sake of fulfilling his dream as a pet shop owner.

The dawn of a decisive battle nears in Leyte Gulf against the Abyssal Fleet, the mysterious enemies that occupy the sea. As the only ones capable of fighting them, Kanmusu—young girls possessing the souls of warships—reorganize in preparation. The Shiratsuyu-class destroyer Shigure is assigned to the First Striking Force, Third Section—also known as 1YB3H. Unfortunately for Shigure, 1YB3H consists of the remaining few Kanmusu and serves as a diversionary fleet. Needing to confront the Abyssal Fleet head-on, it may well be their first and final mission together. Even so, Shigure refuses to let the enemy take another comrade from her. As they advance toward Leyte Gulf during this suicidal mission, the members of 1YB3H must support each other and persevere to prove their worth as competent ships.