WARNING: The following contains spoilers for Season 5, Episode 19 of My Hero Academia, "More of a Hero Than Anyone," now streaming on Funimation, Crunchyroll and Hulu.
My Hero Academia's League of Villains has many members, as well as monstrous creatures known as Nomu. They first appeared in Season 1, but their origins and nature have been largely shrouded in mystery -- until now. The latest My Hero Academia episode, "More of a Hero Than Anyone," sheds light on who makes these abominations and how.
Shota Aizawa and Present Mic visit the Tartarus prison to interrogate Kurogiri, and they learn that Kurogiri's body is based upon that of their deceased classmate, Oboro Shirakumo. As audiences learn in Episode 19 of Season 5, Kurogiri was built by My Hero Academia's own take on Dr. Frankenstein, a wielder of forbidden science.
Quirks initially appear to be a matter of fantasy rather than science, but My Hero Academia slowly and surely explores the true science of how Quirks work, including their classification system. Quirks can be moved from one body to another, like transplanting organs, and it is the villainous All For One who is best at moving Quirks around like that. That talent, combined with the science of the elderly doctor, allows the League of Villains to create lab-grown fighters at will -- the Nomus.
Ordinary, humans cannot easily have more than one natural Quirk factor in their bodies, but the Frankenstein doctor can bypass this limit if he combines dead bodies into a single entity in which All For One can place several Quirks. Early in the series, during the USJ incident, Shota Aizawa and All Might battled a few powerful Nomus, alarmed by the sheer strength and mighty Quirks of these creatures. Each Nomu may be humanoid, but they have unique and strange bodies, even for the world of My Hero Academia. These bodies are due to the doctor's Frankenstein-style science, as he pieces together the ultimate fighters.
Many questions still linger about this topic, such as whether a lab-built Nomu can become immortal, as they are an undead assembly of flesh held together by science and stolen Quirks. If so, All For One and his doctor have found the key to immortality, and there is no sign that Nomus need to eat, sleep or breathe to continue functioning. It's also presumed that these creatures have no memories of their past selves or any personality, but Kurogiri, an advanced Nomu, suggests otherwise.
Unlike other Nomus, which are mindless puppets (as Gran Torino described them), Kurogiri might still have his past memories, and they just might awaken someday. Oboro Shirakumo's body serves as the base for Kurogiri, and All For One's doctor added other body parts and Quirks to him to create the final product. It is currently unclear whether Kurogiri is a special case, or whether other Nomus might have their memories awakened with the correct stimuli, such as meeting a person whom they knew and hearing them talk. If so, the Frankenstein doctor could, in theory, make himself or other villains immortal by placing their brains into a Nomu body, later awakening their memories.
The newest My Hero Academia episode also depicts the doctor in a hospital, watching as Tomura Shigaraki undergoes a harsh medical procedure to become stronger. The doctor calls Tomura a being with infinite power, the "masterpiece" that he and All For One sought to create. Now, Tomura is a lab-grown monster too, Dr. Frankenstein's ultimate abomination against nature.