Explosion

Explosion, read in Japanese as Bakuha, is the Emitter Quirk that belongs to Katsuki Bakugo. It arrives with the series itself in Chapter 1 and Episode 1, and its effective range shifts depending on how he chooses to use it.

Sweat is the fuel. His palms secrete a substance close to nitroglycerin, and igniting it at will produces blasts he sizes to the moment. The resulting fiery shock waves burn and shatter whatever they land on while leaving him almost untouched, aside from minor damage off the recoil. Because the reaction throws off light, it works as a natural answer to Fumikage Tokoyami's Dark Shadow, which is strongest in darkness.

Output scales with perspiration, so the longer a fight drags on and the harder he moves, the heavier the blasts get. It stands as one of the first Quirks the audience ever sees, and alongside Hellflame it carries twelve named Ultimate Moves, a total second only to One For All.

Cold weather slows ignition; warm air is where the sweat detonates best. Sustained heavy use leaves his arms and shoulders throbbing, and firing from both hands simultaneously divides the available force so that each individual blast lands weaker. His palms are the Quirk Factor, so losing them would cost him the power outright.

Borrowing One For All during the rematch against Nine multiplied everything at once: ordinary blasts gouged out craters, and the heat ran hot enough to melt through stone.

The Paranormal Liberation War triggered an Awakening. Rather than one large burst, he could now release several tighter and stronger ones together, a change he later refined into the Ultimate Move Cluster. Cluster layers onto his existing techniques as an upgrade, and though he first assumed it was reserved for desperate moments, he worked out that hoarding surplus sweat beforehand makes the barrage hit considerably harder. Fighting Tomura Shigaraki in the Final War revealed a side effect nobody had anticipated: repeatedly banking those beads had strained the glands in his palms until the sweat began surfacing elsewhere on his body, which let him detonate all over and move far faster at the cost of a constant ache. Against All For One he turned that into control, timing follow-up bursts by where and when the pain struck, and producing explosions roughly triple their usual size.

His Grenadier Bracers exist to spare his body some of that strain. They bank part of his explosive sweat, and pulling a firing pin sets the whole reserve off at once in a blast that punishes the shoulder of whoever fires it, though his physical conditioning leaves him unbothered. He also carries grenade-shaped containers that can be loaded with his sweat and thrown by him or by someone else.

Katsuki is the only holder, and he is openly proud of it. Constant praise for the Quirk in childhood built expectations he could not meet, and the arrogance he wore afterward was cover for feeling inferior. Before U.A. he used it to menace and bully Izuku Midoriya; he has largely dropped that habit, though he still lights small bursts around his palms to unsettle opponents.

The applications run wide: launching himself through the air, blinding foes, throwing blasts at range. Recoil doubles as mobility, and paired with his tactical mind he invents new techniques quickly, arriving at U.A. with several already worked out. He fights all-out, closing distance with propulsion and opening with a heavy right hook, and between that aggression and his ingenuity the Quirk tends to overwhelm whoever faces it. The trade-off is collateral damage, a real liability in hero work that can compromise missions needing a lighter touch, though he has grown more mindful of his surroundings over time.

Named moves include Explosive Speed, Stun Grenade and its point-blank variation, Howitzer Impact, AP Shot with its Auto-Cannon and Machine-Gun escalations, Explode-A-Pult, Land Mine Blast, and Cluster, plus the Cluster-boosted versions of Explosive Speed and Howitzer Impact. His refinement went far enough that a single leftover bead of sweat from Cluster helped restart him internally after Tomura nearly killed him, and he later coated explosive perspiration in ordinary sweat to set a delayed trap for All For One using an external igniter. When his right arm was broken and rendered immobile in the Final War, he refused amputation rather than confine the Quirk to one hand, and steady rehabilitation across the rest of his time at U.A. restored both the arm and the power to full strength.