In My Hero Academia: World Heroes’ Mission, a mysterious terrorist group called the Humanize are introduced. They strongly believe in the "Quirk Singularity Doomsday Theory." The theory states that as future generations continue to be mixed with the Quirk genes, the power it holds will lead to humanity’s demise. Furthermore, Humanize believes that Quirks are a disease, and so, they plan to “cleanse the world” by exterminating anyone who has one. Humanize planted "Ideo Trigger Bombs" in various countries, and these explosives are said to make a Quirk-user lose control of their Quirk, leading to mass destruction. To save and protect everyone, Pro-Heroes from around the world, and the U.A. Academy heroes-in-training, unite to thwart the efforts of the mysterious group.

One year after the events at the Sanctuary, Subaru Natsuki trains hard to better face future challenges. The peaceful days come to an end when Emilia receives an invitation to a meeting in the Watergate City of Priestella from none other than Anastasia Hoshin, one of her rivals in the royal selection. Considering the meeting's significance and the potential dangers Emilia could face, Subaru and his friends accompany her. However, as Subaru reconnects with old associates and companions in Priestella, new formidable foes emerge. Driven by fanatical motivations and engaging in ruthless methods to achieve their ambitions, the new enemy targets Emilia and threaten the very existence of the city. Rallying his allies, Subaru must give his all once more to stop their nefarious goals from becoming a concrete reality.

Years ago, astronaut Byakuya left behind precious materials in the belief that his son, the scientifically-gifted Senkuu, would one day find them. In the present, the Kingdom of Science's Kohaku and Ginrou have infiltrated the harem of the Petrification Kingdom’s leader with the help of Amaryllis, a local girl. At first, their mission progresses without a hitch. Unfortunately, an error enacted by Kohaku and Ginrou leads Minister Ibara and the Island’s strongest warrior, Moz, to identify the intruding duo as enemies. Even worse, Moz tails Amaryllis when she returns to inform Senkuu of the news, discovering the scientist's secret hideout. However, Moz's agenda does not align with Ibara's—he wants to dethrone the minister and keep the petrification device for himself. If Senkuu plays his cards right, he could gain a powerful ally and win the war once and for all.

At the start of her freshman year in college, Hana Uzaki reunites with Shinichi Sakurai, an upperclassman who was in the same club as her during her high school days. However, much to her surprise, the once active senior has ended up becoming a "lonesome" student, preferring to spend his free time in quiet peace. Uzaki does whatever she can to keep Sakurai from being "alone," from convincing him to go to the movies to going to his part-time workplace. While Sakurai finds her irritating and tiresome, he still goes along with Uzaki's hijinks and shenanigans, even if he knows that her perky personality will only lead the two of them into various comical situations. Even so, as the days pass by, their relationship only gets better, to the point where people around them misinterpret them to be a couple. At any rate, whenever Uzaki wants to hang out with her upperclassman, fun and adorable wackiness is sure to follow! [Written by MAL Rewrite]