Yūma is a upper-tier B-Rank Border agent. He was part of Calvaria's army alongside his father when he was still in the Neighborhood, and through unfortunate events he attained a Black Trigger, greatly increasing his combat abilities. As he has been fighting in the Neighbor wars for years, he has a great amount of experience and his combat skills would put him in upper A-Rank.
In addition, he is able to remain calm and think on his feet and is a good tactician even in fierce combat. This was what allowed him to defeat the Aftokrator humanoid invader Viza, who wielded a Black Trigger and was stronger and more experienced than Yuma. He also used his quick thinking to defeat Murakami during the B-Rank Rank Battles even though Murakami already learned to counter Yūma's fighting style with his Side Effect of enhanced sleep learning.
Kazama estimated his level to be around that of a Master Class Attacker, if not higher, as soon as he joined Border. Yoneya described his movements as "quiet, matter-of-fact and deadly", adding that their sole purpose is to take out the opponent as efficiently as possible. This no-frills style reflects Yūma's single-mindedness in combat, which allows him to fight without emotion and makes him one of the only two people in Border not to trigger Kageura's Side Effect.
Due to his years of combat experience, Yūma is adept at tactics. He can pretend to be at a disadvantage in a confrontation in order to cause his opponent to underestimate him, and thus to lower their guard while at the same time reducing the sharpness of their movements when they find themselves unable to land a decisive blow. With this method, he inflicted a crushing defeat on Midorikawa, winning by 8 to 2. Even in their successive matches, Midorikawa could never score more than 3 points out of 10 (9 out of 30).
Thanks to his years of travelling with his father, Yūma has extensive knowledge of Neighbor planet-nations and Trion Warriors.
As someone who has battled from an early age, Yuma is very strong and agile despite his size, being able to fight on par with A-Rank Border agents such as Miwa Unit. His reactions are extraordinarily quick, allowing him to block Asteroid bullets at point-blank range both in his normal and in his combat trion body, a skill he displayed on multiple occasions. He can also block or dodge Eaglet and even Lightning shots, or at least move out of the way enough to avoid fatal damage, even if they are fired by two of the very best Snipers in Border, Azuma and Narasaka. Combined with good spatial awareness, his fast reactions aid him in melee as well, as shown when he managed to dodge the coordinated attacks of two A-Rank agents while refraining from retailating. Later on, he was able to fight off three B-Rank agents at the same time with the help of Osamu's Spider wires and twice without, although in both the latter occasions he lost an arm.
High Trion level: Yūma has a trion level higher than Osamu, making him much stronger and better with even Osamu's weak practice Trigger and his own practice Scorpion.
Trion Body: Yūma is always in a trion body due to his real body being sealed in his ring to prevent his death. This grants Yūma enhanced physical abilities, allowing him to perform many superhuman feats. It also gives him superhuman durability, allowing him to receive most physical attacks with little to no damage, as proven when he was hit by a car and emerging nearly unscathed, with his body quickly recovering. In fact, Yūma's trion body has the unique ability to regenerate itself. In return, its durability is lower than that of ordinary trion bodies. Yūma's trion body also makes it so he never needs to sleep, although he still needs to eat and breathe.
Lie Detector: After receiving a Black Trigger from his father, Yūma also gained his father's Side Effect of being able to distinguish lies from truth. It is not limited to lies alone, as it can also recognize omissions of detail and half-truths. It activates automatically when someone Yūma is looking at lies. When he uses this ability, his pupils become black.
The Trigger Yūma gained from his father to prevent Yūma's death at the cost of his own life, sealing his dying in the ring and replacing it with a self-healing trion one. When activated, it transforms into a fullbody armor, which covers his entire body except his head. This Black Trigger has several abilities which make it considerably versatile. It allows Yūma to generate seals with different effects, as well as to analyze the Triggers of the opponent to create and memorize new seals. Yūma can also combine two seals through Compound Seals, as well as increase their output through Multiplier Seals. Replica often aids him with setting these advanced seals and in the analytical process, but Yūma can do both on his own, although it takes him longer.[BBF Q184] The seals can also be used by Replica independently and by Yūma in his everyday trion body.
The Trigger Yūma chose when he became an official Border member. He is not only extremely skilled with Scorpion, having managed to defeat the No. 3 and 4 Attackers a few times with it, he is also its most prolific user. Through emulation and sheer creativity, he managed to learn all the applications of this Trigger invented by other agents, as well as to develop a few of his own: he has shaped Scorpion like fins to control his movements in strong currents and to bandage a grievous wound in order to stop the initial trion leakage. His combat prowess makes him superior even to most A-Rank agents, as shown by his ability to repeatedly best Midorikawa, another proficient Scorpion user. He primarily fights by dual-wielding it, quickly switching to Grasshopper or Shield when the need arises, but is also proficient with only one. His extraordinary agility, coupled with the lightness of the blade, allows him to land swift, critical attack before retreating just as quickly. He makes full use of Scorpion's ability to be drawn from any part of the body to strike from unexpected positions, increasing its efficacy by altering its shape. At close range, he can throw both Scorpions to finish off an opponent who has lost their balance, a tactic seemingly borrowed from Kageura. Despite his astounding variety of attacks, however, his control of Scorpion's finest techniques was noted to be still unrefined.
Mole Claw (もぐら爪,Mōrukurō?): Yūma causes Scorpion to come out of his sole to attack when his position does not allow him to hit the opponent by wielding the Trigger with his hand. By using it when in contact with a wall, he can aim directly for the target's head.
Leg Blade (脚ブレード,Ashi Burēdo?): Yūma covers his foot and part of his leg with Scorpion, allowing him to cut the enemy with a kick. It can be used to attack from unexpected positions as well as to intercept sword slashes.
Branch Blade (枝刃,Buranchi Burēdo?): Yūma splits Scorpion in multiple blades inside his body and sprouts them from different locations, either to attack from unexpected positions or to defend.
Mantis (マンティス,Mantisu?): Yūma can combine two Scorpions to perform a mid-range attack similar to a whiplash. He is skilled enough to bend it after starting it in order to slip through the opponent's defenses and strike their vitals.
Thanks to his quick reactions and spatial awareness, Yūma is quite adept at using Shield. He can project a large one to defend himself from Gunner bullets while fighting another opponent, or a focused one to counter Sniper Triggers. He is in fact fast enough to deploy a barrier to intercept Eaglet as well as Lightning shots without knowing the Sniper's position, although in the former case he may not generate a shield small enough to block the bullet, and in the latter he is vulnerable to rapid fire. If he does know the direction the attack will come from, however, he can protect himself with a pin-point defense. Yūma often uses Full Guard when he wants to be extra cautious, creating relatively small barriers to maximize protection around his vitals. He was first seen using Shield in Chapter 88 (Episode 40 in the anime).
Since it hinders him in combat, Yūma utilizes Bagworm exclusively for surprise attacks, which he is quite proficient at. He can leave the opponent's field of vision and activate this Trigger to wait for a chance to deal a killing blow. He was first seen using it in Chapter 89 (Episode 40 in the anime).
Yūma was able to employ Grasshopper in combat with great efficacy the day after it was explained to him, possibly thanks to his practice with Bound, and soon after became capable of fighting while in mid-air. Not only he quickly mastered its basic applications, his originality with this Trigger earned him Kōhei Izumi's admiration. His small build gives him an advantage over heavier opponents in aerial combat. Yūma can use this Trigger for quick dodges even while airborne, for hit-and-run tactics, to build up momentum before a strike, and to outmaneuver the enemy, cutting off their retreat. He also utilizes it to rapidly cross the map in order to assist teammates in need, as well as to distantiate himself from troublesome foes, which he primarily does by jumping upwards. While this generally allows him to get out of Attacker range, it makes him an easy target for Snipers. By feinting the jump, however, he can catch the opponent off-guard. In addition, Grasshopper compensates for any impairment to his mobility, such as injured legs or terrains that make walking difficult. In need, he can also propel himself by touching a pad with his hand. Yūma's less conventional applications of this Trigger include using a platform to hurl debris at the target, to boost an ally and to launch an enemy in the air, where they are vulnerable to subsequent attacks.
Pinball (乱反射,Pinbōru;?, lit. Diffuse Reflection): After creating multiple platforms around the opponent, Yūma bounces from one to another at very high speed while slashing at the disoriented target with Scorpion. Between Midorikawa and Yūma, Kō Murakami regards the former as the better user of this technique.
Yūma uses Osamu's Raygust to battle the Mole Mods invading their school in order to avoid being identified as a Neighbor by Border. Despite it being a training Trigger, it allowed Yūma to quickly dispose of the two Trion Warriors. He was able to reduce the size of the blade.
Wire and Dagger
An unknown Trigger Yūma used during his time in the Neighborhood. It summons two daggers connected to Yūma's wrists (to each other in the anime) by a string. Their small size allows the user to hide them under their clothes, a tactic Yūma used to disguise himself as a civilian and then swiftly eliminate the enemy. The string can be lengthened to throw the corresponding weapon and then retracted to quickly retrieve it.