Kazuma is one to not think before he acts, but this proves to be false. He does think, but rather quickly. Kazuma is also known to be headstrong, a trait that causes he and Ryuho to be bitter rivals. He claims he doesn't have a last name on multiple occasions. Kazuma has a unbreakable will and he has proven that under no circumstances will he ever give up or admit defeat. He is also incredibly rebellious and hates the thought of being controlled by anyone. Although he claims to be a selfish Alter user who will do anything for the right price, this is not true as he will challenge any foe and fight against odds to protect innocent people without hesitation, especially the ones he cares for, even at the cost of his life. Kazuma is also obsessed with defeating Ryuho, whom he sees as an enemy. Over time, however, Kazuma grows to respect Ryuho.
Kazuma is first seen attacking the plane Mimori is on, but he is only using it as a means of transport to get to where the HOLY representative is being held captive. After he receives the payment, he heads back home, and, against his better judgement most likely (as usual for the Treasoner), gave most of the money to some kid who's father was injured. He had never met anyone as skilled with Alter power as Ryuho, and Kazuma is soundly trounced in their first fight. However, even as he's confined at HOLY's facility, he refuses to admit defeat. Eventually, with help from Mimori Kiryu, he actually manages to escape back to the outside. As he learns of HOLD and HOLY, and their underhanded tactics, Kazuma begins to focus his attention on them. After the thrashing he got from Ryuho, seeing their darker side just makes him more furious. He yearns to tear HOLD apart for trying to ruin people's lives, and if he can pay Ryuho back for their first encounter, all the better. But with a sense that he isn't yet strong enough, Kazuma does what he does best: pick an option, charge headlong, and don't let anything stand in the way. He heads for the Alter Forest, full of wild animal Alter users in hopes of increasing his power. There, Kazuma comes face to face with a peculiar Alter, one Ryuho had once told him about, The Crystal. In the course of the battle, he manages to rip off the spine of the The Crystal, which immediately grows back, and this evolves his own Alter power, making it much more powerful. When he fights Ryuho the third time, this time with the Shell Bullet, the sheer force of their fight rips open a door to the "Other Side" and throws them into it briefly. In the aftermath of the Second Uprising that he and Ryuho unleashed, Kazuma spends the next eight months fighting in an arena, fighting without a reason, but unlike Ryuho, it seems he has not forgotten anything, as he didn't question who Tachibana and Mimori were. After an encounter with Mimori and Asuka Tachibani however, he begins to pick himself back up and starts looking for Kanami, and he ultimately finds her and Ryuho again at the same time, just before Kanami is kidnapped. He's shown to have a rather simple past with Straight Cougar who had taught him the Bullet techniques.
Shell Bullet Forms
Shell Bullet: The original manifestation of Kazuma's Alter. It is an an alloy-type Alter which transforms his right arm into a weapon. After de-materializing the sufficient quantity of matter (typically, the mass stored in a small automobile), Kazuma transmutes it briefly into Alter energy before reforming it into matter enameling his right arm. At its first level, Shell Bullet covers Kazuma's right arm with protective metal armor, which is mostly golden in color but with orange and gray sections also, Kazuma's right hand is divided into orange and red plating, with metallic claws for fingernails and creates three red curved fins of metal jutting out from his right shoulder blade that store potential "Alter" energy, each progressively larger as they near his shoulder (in actuality, it is the middle fin that is the largest one). The fins break apart & release the potential Alter energy that burst outwards to propel Kazuma forward at great speed, increasing the power of his strikes, which Kazuma labels as Bullets, giving them names that represent their power or affect on the opponent.
- Fissure Uplift: By punching the ground with "Shell Bullet" and channeling Alter energy into it, Kazuma can generate a small fissure of energy that stretches for about a dozen or so meters, which in turn unleashes a powerful force sufficient to easily launch several humans into the air and away from Kazuma.
- Shōgeki no Faasuto Buretto (衝撃のファーストブレト, Shocking First Bullet): The first of the three "Bullets" that Kazuma can use in this Alter stage. Shattering the most downward fin (the smallest one), Kazuma begins to slide across the ground and pivot repeatedly in order to either maintain or increase his momentum, before thrusting his fist at the target and unleashing a powerful wave of force. Kazuma managed to collapse an entire office building by striking its top surface with "Shocking First Bullet".
- Gekimetsu no Sekando Buretto (撃滅のセカンドブレト, Destructive Second Bullet): The second of the three "Bullets" that Kazuma can use in this Alter stage. Functions the same as "Shocking First Bullet", except that it is the middle/central fin that gets destroyed and the firepower is increased: Kazuma was capable of destroying the large, steel entrance gate to the "Lost Ground" city with this move (likely approaching city block-busting levels, given the quantity of reinforced steel present). Called Annihilating Second Bullet in the English dub.
- Messatsu no Rasuto Buretto (滅殺のラストブレト, Obliterating Last Bullet): The third and strongest of the three "Bullets" that Kazuma can use in this Alter stage. Functions the same as "Shocking First Bullet" and "Annihilating Second Bullet", except that it is the highest fin that gets destroyed and the firepower is further increased: This is the attack that ranks Kazuma at multi-city block-busting power, capable of wiping out hundreds of thousands of cubic meters worth of rock in energy collisions with equally-powerful "Alter" users. Called Exterminating Last Bullet in the English dub.
Shell Bullet Ultimate: The first evolution of Kazuma's Alter, attained after "Shell Bullet" interacted with material native to the "Alter" parallel dimension (namely, a piece of The Crystal Alter's rib-cage). After matter is de materialized and reformed onto Kazuma's right arm, it now takes the appearance of a predominantly-orange plating that now extends across half of the limb's length before segmenting in half with a red, shoulder guard. The armor is thicker and is later revealed to replace his entire arm instead of simply covering it. For some reason, whenever summoned, it possesses a small, grey or silver brace on its wrist that falls off when used, possibly serving as a sort of temporary lock until he decides to use his arm. Four orange fins appear/extend around the right side of Kazuma's face (towards his eye), and a large golden propeller located where the three red fins used to be. This propeller grants Kazuma flight, as well as eliminating the firing limit imposed by his first form. On his fist is a small aperture which can absorb additional Alter power, further strengthening his attacks, which he calls Shell Bullets. This stage of Shell Bullet is the only one that demonstrates regenerative properties, as it was once damaged and severed from Kazuma's body and then reattached itself to him by de-materializing and reforming on him.
- Shell Bullet: Uses the propeller on his back to propel himself forward while gathering alter energy from the duct on his arm, this was the technique he used when he caused the second upheaval of the grounds with Ryuho.
- Energy Absorption: The aperture duct embedded into Kazuma's right hand is capable of absorbing atmospheric traces of "Alter" energy in the local environment and redirecting it into his personal reserves. This is the primary method of "Shell Bullet Ultimate", with Kazuma gaining the energy needed for his special attacks.
- Shell Bullet Burst: Kazuma channels all of his collected Alter energy into the aperture of his propeller, causing a blinding golden light to emit from his right hand, before throwing a punch at a target. The resulting strike releases all of the energy in one blast, extending well beyond Kazuma's mêlée range (effective to at least a few dozens of meters) and retaining the golden luminescence in the shape of a fist. Capable of immediately disintegrating the structure of Biff's "Hammer" Alter after its refinement.
Before charging up the propeller, he uses his aperture duct to gather energy. While gathering this energy, he has a habit of shouting phrases "Shine brighter!" or "More power! AND MORE!! AND MORE!!!!"
Proud Fist Form
Proud Fist: In his final form, achieved from pushing himself and his ability beyond his natural limits with his resolve to defeat Kyoji Mujo and avenge all of his fallen comrades at the hands of the mainland Alter user. Kazuma's Alter, which previously extended only the length of his right arm and individual pieces on his right shoulder region, now traverses across his entire form as a type of "bodysuit", streamlined to his body and sharing the same color scheme as his right arm. The four-fin face-pieces have now fused and extended across to form a mask, while a large wave of jagged, red "hair" juts upwards from the mask, causing him to appear as a humanoid cross between a samurai and a lion.
His Alter energy-absorbing arm grows even larger than his second form and in addition, his left arm becomes armored and possesses an aperture duct, and his propeller is replaced by a long, flexible, tail-like appendage which acts like a whip, serving much the same purpose as the fins from the first form or the propeller in the second form did (no longer requiring the latter with free-form flight), acting in the same manor as an anti-gravitational propulsion unit used to push himself wherever he wished to soar at high speeds. In addition to this appendage, a secondary, smaller one appears on the back of his left side (which could indicate that his final form could become much stronger over time, as the smaller appendage may grow to the size of the whip on his right side). After using this power, Kazuma has several connecting scars on his arm that originally held his Alter power at stage 1.
- Dimensional BFR: With his humungous boost in raw power, "Proud Fist" Kazuma can distort the fabric of space with his punches and voluntarily tear open a rift to the "Alter" dimension parallel to the real world. From there, he can throw opponents inside to trap them within permanently, and only fellow "Alter" users that attain a similar "evolution" to Kazuma or Ryuhou are capable of escaping from the parallel realm (the mutated Kyoji Mujo). The tear can extend for up to several kilometers in horizontal length (left to right, vice versa).
- Giant Explosion Fist: "Proud Fist" Kazuma can also generate incredible, raw firepower from his standard punches, with individual strikes ranging from over a hundred to several hundred kilometers in width and are capable of breaching past Earth's orbit when concentrated into beam form, or expanding across a large portion of the planet's surface (easily viewable from outer space).
Shell Bullet: An "augmentation"-style "Alter" manifestation. While typically used by Manga Kazuma as an immense boost in physical attributes, especially physical strength, and range-of-effect with his punches like his anime counterpart, "Shell Bullet" in the manga also has some more exotic properties: it appears to possess a natural adaptability system which enables it to interact with concepts such as souls of the deceased, other "Alter" manifestations and even its own shape in order to maximize its effectiveness potential in battle. The characteristic three fins, which represent the limitation of full-power punches Kazuma can perform in the anime, notably do not shatter upon using a full-power punch, meaning that Manga Kazuma has effectively unlimited usage with "Shell Bullet".
- Empathetic Empowerment: Manga Kazuma does not use "Shell Bullet" at full-power by tapping into dormant reserves within the "Alter" itself (as within the fins in the anime), but rather by experiencing powerful emotions and using such personal conviction to augment incoming blows. This is usually expressed by Kazuma shouting "Shell Bullet of -" with the - depending on the exact type of emotion he is feeling (i.e, anger = "of Rage"; remorse = "of Grief").
- Soul Absorption: Manga Kazuma has the ability to temporarily assimilate the spirits of deceased individuals into his "Alter", storing them in what appear to be small capsule-like rods on "Shell Bullet", that are discarded once the spirit departs Kazuma. The spirits appear to be capable of enhancing Kazuma's physical stats, but their most dangerous application is the transfer of their knowledge and memories from Kazuma to an opponent via physical contact, forcing the target to experience the life of a victim they murdered or harmed in visions. The aftermath of such events often lead to complete mental breakdown.
- Ability Replication: Another ability of Manga Kazuma is the trait of his "Shell Bullet" to temporarily absorb the attributes of another "Alter" through unknown means. This is only seen in effect against Cougar's speed "Alter": the first time to avoid an incoming "Cougar Speed" attack. The second occurrence is debatable, and if true would indicate that the ability-replication effects are infact long-term: Kazuma appears to boost himself in the air to reach HOLY's headquarters with Cougar's speed.
- Body Alteration: "Shell Bullet" is shown to be highly versatile even in the arrangement of its physique: Kazuma demonstrates this by arranging the structure of the arm into a mirror, in order to reflect the magnified light generated by Aono's "Shield of Distortion".
- Healing Acceleration: Presumably through his ability to deconstruct/reconstruct matter, Manga & Anime Kazuma demonstrate vast recuperative abilities via various showings. Once having his arm lopped off by Ryuho's evolved Zetsui only to reattach it using his Alter Power, while the Manga only version uses the power to forcibly permeate medicine through his skin and directly into his bloodstream, massively accelerate his healing factor rate and recovering from injuries in minutes, what would normally take days or weeks to naturally heal. Forms prominent spikes around his body wounds in the process.
Death Bullet: The evolution of "Shell Bullet" following Kazuma's experience of the "s-CRY-ed" word. A full-body "augmentation"-style "Alter" transformation. Presumably retains all the abilities demonstrated by the previous "Shell Bullet" form, plus with massively increased physical attributes and a single, highly potent effect addition.
- Effect Reversal: A highly potent ability of "Death Bullet" Kazuma is his power to "reverse" the position or nature of any physical or energy-based ability with physical contact. First seen when he reversed the lens of Aono's "Shield of Distortion" so that the magnification process minimized from Aono's position and maximized on Kazuma's.
- Fist of Pride: Manga Kazuma's ultimate punch and used to kill Galan Du. The force of this punch was sufficient to fire its effect as a beam of energy escaping into outer space and still form a crater hundreds of meters wide on the ground.
Mental Treason: A powerful skill, described by Cougar Straight as the ability to "think weak" and to forcibly suppress those detrimental thoughts to ensure that Kazuma will enter combat with full confidence in his own capabilities. This is the origin of Kazuma's moniker "Treasoner" and the reason why he will never consider fleeing from a battle; he was even capable of continuing to fight after experiencing a death premonition from Aono that completely paralyzed a veteran Alter user and fighter, Akira Mijyou, in her tracks.
- Oddly though, he is the only one who has a non-Alter part that changes when he activates his Alter. His hair changes from brown in a tamed style to red in a wild style.
- Interestingly, it seems his right eye became part of his Alter's second and third stages, and the iris became a brighter color.