A. Phex Brothers
The twin brothers are Rock Humans belonging to the Locacaca Organization as assassins. They hunt down Karera Sakunami for her knowledge concerning the Locacaca and clash with Josuke Higashikata. They are both Stand users who wield their Schott Key No.1 and Schott Key No.2 in unison.
Although both brothers are identical in appearance and attire, they have small differences to distinguish one another. Besides the elder brother's damaged right arm that has Schott Key No.1, the elder brother has his ear piercing on his left ear whereas the younger brother has his on his right ear. Sporting nearly shaven heads with intricate sideburn designs and neck-length ponytails, they wear long-sleeved decorated shirts and shorts which are reminiscent of typical footballer clothing, the latter of which were first shown to have a serrated bottom. Their eyes are squinted to the point of appearing shut a majority of the time.
The pair share a duality described as harmonious with one another, being based on the Japanese concept of 'A-un', which explains the connected nature of opposites and their seemingly contradictory similarities.
Aside from that, the elder of the two brothers seems to be the one in charge, and was the only one to speak at first, but the younger brother speaks as well later on. The elder brother is the one who communicates with the policemen in place of his brother and the one who displays a Stand power; his brother however would later reveal he also possessed a Stand - hidden in his soccer ball bag. The younger brother is more reserved, preferring to let his older brother do most of the talking. The younger brother also has a habit of kicking around his Stand's container and performing tricks with it, not unlike, and in the guise of, a soccer player. In fact, he is said to have kept a ball with him at all times ever since he was a kid.
As twins, the A.Phex Brothers get along well and the older brother even protects and supports his brother, saying that it is not his fault that he attracted attention by playing with the ball. The two have also developed good teamwork in combat, using their abilities in unison to take their enemies by surprise.
As members of the Locacaca Organization, the A. Phex Brothers are quite accustomed to violent actions towards those in their way. They brutalize a couple of policemen who wanted to arrest them, set Karera Sakunami on fire to dispose of her and when Josuke interposes himself, they quickly decide to kill him as well. They do show some restraint and are able to calmly ask random citizens about the whereabouts of their target.
Schott Key No.1
- Main article: Schott Key No.1
The Stand of the elder brother, Schott Key No. 1, can shift objects touched with his left hand to the stub on his right. He can manipulate the way it materializes for a variety of strategic advantages. The first example of this is shown during the confrontation between the brothers and a pair of police officers who attempt to ascertain the identity of the brothers. Objects transported in this fashion will seem to break down and crumble while the material reassembles on the other end.
Schott Key No.2
- Main article: Schott Key No.2
The younger brother's Stand, Schott Key No. 2, possesses the ability to release potentially fatal toxic gas whenever the Stand's container is opened. Its effect induces a bloody cough when inhaled, and quickly corrodes skin that comes in contact with it. The gas can be transported by Schott Key No. 1 to give the elder brother a deadly technique in combat.
While similar to a human's, their bodies can presumably change into rock. Because of this, they do not need to sleep or rest. They can mimic rocks to the point that it makes them indistinguishable from them.
Norisuke theorizes that Yotsuyu's physiology requires him to have at least a small amount of skin respiration and in the absence of such his body structure will begin to break down due to it becoming less structurally stable than an ordinary human's. This could be a trait shared by other Rock humans, including the A. Phex Brothers.
The younger brother demonstrates versatile and dynamic control of his soccer ball common of experts, capable of moving it between his legs and head effortlessly and kicking it with enough force and power that it could be considered an attack of its own.
On August 19, 2011, the A. Phex Brothers were sent to assassinate Josefumi Kujo and Yoshikage Kira. The A. Phex Brothers found him near the coast approached him from the forest. The brothers confirmed to Yagiyama the location of the Locacaca and went for the kill, the younger brother kicking his ball toward Josefumi. Suddenly the ball floated away, as Josefumi had filled it with bubbles, enabling him to break the Rockman's leg with a well-placed kick and repeatedly stomp his head. The elder brother intervened and arm locked Josefumi, who retaliated by bursting bubbles near a branch to propel it toward the elder brother's head and impales him. Incapacitated, the A. Phex Brothers were then pummeled over the cliff by Soft & Wet. They were subsequently sent on Karera Sakunami's trail, chasing her for six months.
As Josuke and Karera walk away from the ATM, the brothers can be seen questioned by a pair of policemen as to the strange nature of their ball and what one officer perceives to be a rock held in the hand of the older brother. After he demonstrates his ability in subduing the policemen, dialogue exchanged between the two brothers suggests that they have been hunting Karera and are surprised she has lasted this long.
Searching the streets for people who have come into contact with Karera, they eventually run into her and Josuke when the pair are nearing Kira's apartment. The elder brother sneaks up behind Karera to use his power to cover her in the fuel of an adjacent vehicle by transporting it out of the tank. He sets her ablaze and considers their target done for. To the surprise of the twins, Karera is saved by a myriad of mysterious soap bubbles which put out the flame before it can do any lasting damage to her. Revealing his power Soft & Wet and telling Karera to flee, Josuke engages in combat with the brothers who shift their attention to him.
The elder A. Phex Brother uses his Schott Key No.1 to transfer wires around Josuke's head to bind him. At the same time Karera changes her mind and decides to come back to help. The younger A. Phex Brother remarks Josuke's ability is similar to Kira's, but his brother decides to kill him anyway without asking questions. The younger A. Phex Brother then reveals his Stand Schott Key No.2 hidden inside the football and prepares to kick the ball toward Josuke, who uses Soft & Wet to propel several bolts at the brothers. He uses the distraction to free himself from the wire and fights personally with the youngest. Josuke easily dominates the Rock Human in the fistfight, managing to land several hits while protecting himself from Schott Key No.2, but the younger A. Phex Brother manages to get away and still juggle with the ball. The football suddenly disappears, and Josuke realizes it is now falling on his head. Schott Key No.2 releases a toxic and corrosive gas from which Josuke manages to partially protect himself from with a bubble wall. Yet the gas comes in contact with Josuke's leg and he suddenly feels weakened. As the A. Phex Brothers surround Josuke, he grasps Schott Key No.2's power.
The elder brother grapples Josuke from behind while the younger brother kicks his ball near them. The elder then puts his hand inside the ball, but Josuke warns him not to transfer the poisonous gas from hand to hand. The Rock Human does it anyway and Josuke's bubbles instead appear from his right hand, as Josuke planted the bubbles full of gas inside the ball; the bubbles surround the elder. Before the A. Phex Brothers can react, the elder is set on fire by Karera who used the latter's lighter and burned a wick made of hair to ignite the gasoline which is still covering him. The elder A. Phex Brother panics and runs toward the younger, which is when the bubbles full of poisonous gas pop and kill both brothers.