Permeation

Permeation is a close range Transformation type Quirk carried by Mirio Togata, and by his father before him. It renders the body intangible so that it passes through any matter. The holder picks whether to affect one part of themselves or all of it, which allows smooth movement through obstacles and effortless evasion. Switching it off while inside solid material ejects the user to the surface instantly, since two masses cannot occupy the same space.

Mirio's father warned that mishandling it can kill, and the power is notoriously hard to control. Phasing through a wall without dropping through the floor demands a precise sequence of body parts going intangible while others stay solid, every step needing full concentration, though training has made it near automatic for Mirio. Clothing does not come along and tends to fall away the moment the Quirk activates. Garments woven from the user's own hair are the exception, which is why Mirio's costume stays on.

Going fully intangible while standing means gravity drags him straight down through the ground. In that state his senses die as well, since light, air, and sound pass through him too, leaving only the feeling of falling. Intangibility covers only the user and never anyone else, so a person he carries stays exposed, and dropping the Quirk to shield them puts him back in danger. All For One observed that unpredictable attacks beat it: Mirio was pierced from behind by "Tomura" and Rivet Stab before he could react.

Mirio grew up knowing the danger and never wavered on becoming a hero, despite struggling so badly that a plank of wood defeated him in middle school. Sheer persistence carried him far enough to clear the U.A. Entrance Exam. His showing at the following Sports Festival was unremarkable, but Sir Nighteye still spotted a potential successor to All Might in him, and a brutal internship regimen brought him to near flawless control, the clothing problem solved by a costume made from his hair.

He applies the power with surgical timing in the middle of fast movement, which makes guarding against him essentially impossible, and he mastered the ejection property into a form of instant travel, steering his falling body to resurface beside a target and strike from any angle. To onlookers he appears to teleport, vanishing and reappearing almost immediately. He has also held incoming energy inside himself to power his blows, as when Nejire Chan fed him Wave Motion. His named techniques include Blinder Touch Eyeball Crush, a feint jabbing at an opponent's eye with an intangible arm before the real strike lands, first used on Izuku Midoriya, and Phantom Menace, in which he flicks the Quirk on and off to catapult himself off walls, floor, and ceiling at rising speed while battering his targets, which he debuted on Deidoro Sakaki and Shin Nemoto.