Katsuki is a young man of average height, with ash blond, spiky hair and red eyes. At school, he wears the standard U.A. uniform, save for the customary red tie. Underneath his blazer, he wears a white button up shirt, but keeps the first couple buttons unbuttoned. Despite wearing a belt along with the uniform's green pants, he does not pull them up all the way, giving his pants a baggy appearance.
His hero costume is composed of a fitted black sleeveless V-neck tank top with an orange X with the top half borders his shirt collar. His costume also has a seemingly metallic neck brace fashioned and used as a collar with three holes in both sides. His sleeves reach from within his large grenade-like gauntlets to his biceps. His belt, which also carries grenades, holds up his baggy pants with knee guards. He occasionally wears his hero mask that has large, flare-shaped cloth.
Katsuki is a very crude, violent, arrogant, and aggressive person that has a tendency of bullying Izuku Midoriya, who he often viewed as an obstacle to be surpassed, but now treats him more as a rival.
Brutal and bloodthirsty, he smiles eerily when he's put into battle. While battling, his personality reflects his fighting style. His brutish way of fighting is shown through the Battle Trial Arc: mercilessly assaulting Izuku and having no regard for nearby objects, merely destroying them with his power. Despite this, he's quite talented in fighting, able to use his Quirk to not only destroy but to maneuver around the battlefield. He's also very intelligent, being capable of strategic planning and holding some of the highest grades in his class, to the point that some even consider him a genius.
While not the most mentally stable hero-in-training, nor having the image of one, he knows who his enemies and allies are. Cold to his allies, though not to the extent of friendly fire, but colder and brutal to his enemies. He's also very rude and foul-mouthed, which makes him unpopular with most of his U.A. classmates. As the series progresses, his outbursts become less aggressive, usually becoming more comical, as he mostly gets angry at even small things like teasing. With that in mind, Katsuki seems to mature slowly but is still quite aloof and unsociable, showing disinterest in hanging out with his fellow classmates.
Katsuki's aggression is reflected in how he uses his Quirk. He tends to completely disregard the notion that Quirks shouldn't be used in public, and will activate his Quirk for a number of reasons, such as to intimate someone, to punctuate a point, out of frustration, or even if he just feels like showing off. When in combat, he will often set off smaller explosions in his hands, and sometimes will detonate even larger ones, when he's not even attacking, which highlight his aggression, particularly in combat. He thinks little of the laws regarding Quirk usage, and even berated Izuku for not using his own Quirk against Shigaraki in public.
Due to the constant praise of his abilities and his powerful Quirk, Katsuki has a superiority complex and wants to be first and the best at everything. He doesn't like when people look down on him, as if they were superior; thus, it diminishes his already short fuse. Despite his extreme arrogance, he also thinks of people such as Izuku Midoriya as an obstacle on his path to becoming the greatest hero. Because of his complex, he's implied to be anti-social; He seems not to care for much people as he doesn't remember his classmates' Quirks or names despite being in U.A. for some time. He does, however, remember the names of people who give him a challenge or whose ability he respects, such as Ochaco Uraraka and went as far as to defend her when his classmates referred to her as a fragile girl.
Katsuki is also immensely prideful, as he hates the idea of others either helping him or him having to rely on others to assist him in battle. Because of his pride, Katsuki refuses to work together with others claiming he can do whatever he's assigned on his own. His pride has cost him on numerous occasions: he lost the Battle Trial due to his lack of cooperation with Tenya, he was effortlessly defeated by All Might in the End of Term Exam and only passed once he finally accepted to work together with Izuku. However, he will repay those who help him, such as when he gave Eijiro the money for his broken night vision goggles when he came to help rescue him.
Ironically, his inspiration for becoming a hero was the same as Izuku's, the Symbol of Peace, All Might. However, their beliefs differ: Katsuki feels a hero should never stop fighting or give up, regardless of the threat they face, and that always winning is the mark of a true hero. Furthermore, because of his arrogant and conceited behavior, various heroes, civilians and even villains have commented on his villain-like behavior. However, Katsuki is unwavering in becoming a hero, having outright refused Tomura's acceptance into the League of Villains.
Quirk and Abilities
Explosion (爆破 Bakuha?): Katsuki's sweat on his palms are nitroglycerin-like, and he can use it to create explosions. The more Katsuki sweats, the stronger his explosions become. So far, the signature use of his Quirk is through his hands; usually between punches or to shroud his fist with explosive energy. Katsuki's most powerful Explosion so far (without the need of the Grenadier Bracers) was able to completely destroy Ochako's meteor rubble shower, knocking her down onto the ground at the same time and causing a shockwave that was felt throughout the stadium. Due to his extensive combat knowledge and creativity, Katsuki's Explosion Quirk has shown to be deadly and versatile.
Katsuki does not suffer from the impact of his explosions, thus giving him an immunity to his own explosions. He is able to set off constant explosions around him without feeling any negative repercussions. It is currently unknown if he can be affected by explosions from any source other than from his own Quirk; Although, during the Sports Festival's first obstacle, Katsuki was able to navigate through the landmines without being harmed.
One drawback of Katsuki's Quirk is that he is unable to use his explosions in areas filled with flammable gas as his explosions would ignite the gas and spread it further. Additionally, because his Quirk relies on his hands sweating, it is more difficult for his Quirk to work in colder climates . Without sweat from his palms, he cannot use his Quirk to it's fullest potential.
- Blast Rush Turbo (爆速ターボ Bakusoku Tābo?): Katsuki throws his hands backwards and then causes an explosion in his palms, to propel himself forward. This move can also be used to achieve a pseudo form of flight, as Katsuki used this move to fly over the giant robots during the Obstacle Race during the Sports Festival.
- Stun Grenade (閃光弾 Sutan Gurenēdo?): Katsuki creates a sphere of light with his hands. The sphere of light implodes, causing an explosion around Katsuki, blinding anything in Katsuki's vicinity.
- Howitzer Impact (榴弾砲着弾 Hauzā Inpakuto?): Katsuki dashes into the air and creates two Explosions in his hands. While in the air, Katsuki spins himself around, building up momentum for his Explosions. After spinning himself around and gathering momentum for his Explosions, Katsuki fires an Explosive tornado at his opponent.
- AP Shot (徹甲弾 (A・P・ショット) AP Shotto?): Katsuki's special move. Katsuki stretches out one of his hands and uses his other hand to form a circle on the palm of his outstretched hand. Katsuki then fires an explosion through the circle, which creates a concentrated blast beam. By focusing his the path of his explosions into a single point instead of around his whole palm, Katsuki creates a concentrated blast with reduced area of impact, but with enough power to successfully pierce even solid concrete.
- AP Shot: Auto-Cannon: A rapid-fire version of his AP Shot technique. The explosion power is reduced in order to avoid dealing severe damage to human targets.
Overall Abilities: Katsuki has shown to be one of the strongest students on Class 1-A. He was able to defeat Fumikage Tokoyami and Shouto Todoroki during the Sports Festival, people who are also considered to be quite strong (although they had disadvantages respectively in their fights against Katsuki but despite these limitations they still proved to be strong). Many notable Pro Heroes such as Shouta Aizawa and All Might have praised Katsuki's prowess; even the League of Villains have taken notice of Katsuki's strength and went as far as kidnapping him even if it meant losing members of the Vanguard Action Squad.
Enhanced Strength: Katsuki possesses an above average physical strength, as he was able to fight on par with Izuku even when the latter is using his Quirk. He was also able to pressure and overpower Shouto Todoroki, a powerful combatant, during their battle.
Keen Intellect: Katsuki has proven to be very smart and strategic, as he was able to figure out Kurogiri's Quirk weakness and Fumikage's weakness in a short period of time. Additionally, he quickly assessed which of the attacking villains in USJ was the most dangerous threat in the long term. Even Pro Heroes (such as All Might) have mentioned several times his great potential and battle-sense. Shouta Aizawa stated that in battle Katsuki shines his brightest.
Grenadier Bracers (籠手 Kote?): An adjustment added to Katsuki's hero costume that stores his nitroglycerin-like sweat. Once filled he can pull the grenade pin in order to release a large blast. As shown when he fought Izuku in All Might's Heroes vs. Villains test. It has enough explosive power to destroy all parts of the building within its blast radius. This equipment was first used during the Battle Trial.
Improvised Grenades : Around the belt of his Hero costume, are several containers made to look like hand grenades. These can store Katsuki's nitroglycerin-like sweat, and be used as regular grenades at a later time. These were first used in a practical way during the Provisional license exam by Denki.
Knee Pads - These are very blunt metallic attachments to Katsuki's knees. They are designed so he can "kill with his knees", but he has not displayed such use for them as of yet.
- Katsuki likes spicy food and mountain climbing.
- Originally, Katsuki was supposed to be a natural born genius, a very kind and gentle character who spoke without thinking and unintentionally insulted others. The author, however, found this original draft to be boring and decided to make him an unpleasant character instead.
- Katsuki is student no.17 in Class 1-A.
- Katsuki ranked 1st during the Entrance Exam and 3rd during the Quirk Apprehension Test.
- Katsuki's rankings in the Popularity Polls are as follows:
- Katsuki ranked 3rd in the First Popularity Poll.
- Katsuki ranked 1st in the Second Popularity Poll.
- Katsuki's name is composed of "爆" (baku?) from "爆破" (bakuha lit. "explosion"?) and "勝" (ka(tsu)?) from "勝つ" (katsu lit. "to win"?).
- Katsuki ranks 3rd in Class 1-A's Grades.
- Katsuki was the winner of The U.A. Sports Festival First-Year Stage.
- (To Izuku Midoriya) "From here on, I..! From here on..! Y'hear me?! I'm gonna... beat you all! Enjoy your win. It'll never happen again! Dammit!"
- (To All Might) "Needless to say... I'll be a hero that surpasses even you!"
- (To Shoto Todoroki) "You'll regret making a fool of me! I'll freaking kill you! I'm taking the first to end all firsts! There's no point in winning against some half-assed punk! No point if I can't do better than Deku! So if you're not trying to win, get the hell outta my face! Why're you even here, you bastard?!"
- (To Izuku Midoriya) "Stop talking. I will win. That's... what heroes do."
- (To the League of Villains) "Can't stand morons like you who can't get to the damned point! Basically you're saying, 'we wanna cause trouble, be our pal!' What a joke! I've always admired All Might's triumphs. No matter what any of you jerks say... Nothing's ever gonna change that!"