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.