Nomu

They begin as human bodies floating in tanks. The engineering that follows warps them into something bulkier and stranger than anything they were in life, shaped around whatever the Doctor needs them to survive, and the finished product almost always wears its brain on the outside. The name reads as brainless, which is either ironic given the exposed organ or perfectly accurate given that nothing is happening inside it.

Skin color sorts them: the Lower-Tier come out pale, the Middle-Tier in more vivid shades, and the Upper-Tier in black. Beyond that the silhouettes are individual, wings on one, six tool-tipped arms on another, a mouth-first lamprey shape on a third. Garaki modeled the whole line on Gigantomachia, whose ability to hold several Quirks at once made him worth copying.

The core trick is capacity. Human experimentation ends all higher brain function, leaving the subject with no will and no ability to act until a superior tells it to, and in exchange the body can carry multiple Quirks. All For One granting those Quirks is what makes production viable; without him, Garaki transplants each one through elaborate surgery.

Garaki and All For One sort their stock into five grades by physical enhancement and Quirk count. The Lower-Tier are foot soldiers with one or two Quirks who need a keeper's spoken order to attack, though even they can run over a minor Pro Hero. The Middle-Tier improve on that, covering things like Tool Arms. The Upper-Tier come with Super Regeneration and Shock Absorption and rate at ten average people apiece by Garaki's math. Near High-Ends are the top grade caught mid-production: as fast and strong as the finished article and completely unable to think.

The High-Ends outclass everything, carrying up to six Quirks, and what actually separates them is that they talk. The advanced ones think independently and keep the personality of whoever died to make them, which is why Garaki picks only the most battle-hungry villains as candidates, and each takes complex surgery plus three months minimum of stabilization. They deduce fast, too: Hood picked apart the limits of Endeavor's Quirk in moments.

The earliest one is Kurogiri, built from the body of the U.A. student Oboro Shirakumo, his Cloud Quirk used as the foundation for an artificial Warp Gate. He can speak and think freely, designed as a reliable pair of hands first for All For One, then as the minder assigned to Tomura Shigaraki, and traces of Oboro's caring nature survive even though the memories do not. After All Might defeated All For One, he and the Doctor began work on something that could match the Symbol of Peace, which became the point of the entire project.

The first true Nomu appears at the U.S.J., purpose-built to kill All Might with Shock Absorption, Super Regeneration, and engineered strength, and it loses to attrition when All Might simply hits it faster than the healing can keep up. Police analysis of its DNA reveals a small-time thug rebuilt to hold multiple Quirks, which is how Naomasa Tsukauchi first traces a line to All For One. Three more wreck Hosu City: Gran Torino kicks down the white one, Endeavor cauterizes the black one past regeneration, and Stain kills the winged one after it snatches Izuku Midoriya. A Chainsaw Nomu joins the Vanguard Action Squad in the training camp forest and leaves with Momo Yaoyorozu's tracking device welded to its back, which hands the Heroes the Kamino factory and thirteen Nomu in storage.

Then the grades escalate. Dabi is entrusted with Hood, the first High-End, which devastates Fukuoka and overpowers Endeavor before Endeavor and Hawks burn it past recovery, and Garaki shows Dabi twelve more in stasis, at which point Dabi recognizes the procedure that rebuilt his own body years earlier. Kurogiri is what unravels it all: Gran Torino and Naomasa learn he was made from Oboro and coax one word out of him, hospital. Mirko tears through the Jaku laboratory, five untested High-Ends are unleashed against her and Crust, and Tomura wakes, decays every activated High-End, and rouses the unfinished stock. After the war an imprisoned Garaki gives up the rest, and the captured Nomu go to Central Hospital so his information and their biology can serve restorative research. Neito Monoma's copy of Kurogiri's Quirk scatters the last Near High-Ends across Japan in the Final War, where they are beaten one battlefield at a time, and with Garaki jailed and All For One dead no more can be made. That research is ultimately what saves Spinner's mind from dissolving under his extra Quirks.