Claustro

Claustro is the short name. The patent title Detnerat gave it runs much longer: a Burden-Amplifying Steel Pressure Mechanism, tagged Claustro. Rikiya Yotsubashi is the man it was built for, and the weapon turns up first in chapter 238 of the manga, then in episode 112 of the anime.

One wearer only: Re-Destro, who leads the Meta Liberation Army as its Grand Commander. Its job is to push Stress, his Meta Ability, to 150 percent of normal or higher. The parts are mechanized drones parked below ground. Summoned, they break the surface, converge on his hugely enlarged frame, and lock together into armor around him. He can scatter the pieces again at will and send them flying independently. Tomura Shigaraki wrecked the whole thing during their fight.

Nobody but Re-Destro wears it. The name almost certainly draws on claustrophobia, the terror of being shut into a space with no way out, which describes a man who seals himself inside a machine so the confinement will feed his power. Iron Man's Hulkbuster invites comparison too, since both are assembled from many parts kept out of sight until the moment they are called.