Juan was an amateur boxer and a hopeful of the Olympics, however, he lost in the qualifiers. He immediately went to professional boxing with his family as his seconds, including his former world ranking uncle as his chief trainer. After his professional debut, he had a sixteen winning streak with fourteen knockouts and became the WBA lightweight world champion. In his second title defence, he was defeated by an attack to the body and lost his title. Juan disagreed with the outcome, believing that his title was stolen from him. Soon after losing his WBA lightweight world title, Juan had a match against former OPBF lightweight champion Ryō Mashiba scheduled, where the winner is promised a world title match afterwards. Juan planned to win in order to face the champion again.
On the day of Juan's world title preliminary match, Juan went to the Kōrakuen Hall. Juan arrived to the ring as the match was about to begin. As the match began, Juan dodged a left jab from Mashiba and threw an overhand, which landed on Mashiba's block. As Mashiba used footwork to get away, Juan went to the centre of the ring and made sudden movements that caused Mashiba to go along the ropes, letting Juan catch him with a right on his guard. Juan got into his rhythm, throwing lefts and rights at various angles to Mashiba's guard while weaving side-to-side and mixing feints in. After Juan shoved open Mashiba's guard, he hit him on the body. Mashiba moved away as Juan gave chase. Juan attacked Mashiba's guard when he got close and threw a feint to the head, tricking Mashiba, and letting Juan hit him on the body again. Juan soon feinted another punch to the head, tricking Mashiba again as Juan lands another body blow. The round ended as Juan was about to throw a follow=up punch while Mashiba was reeling in pain. At his corner, Juan could tell by his eyes that Mashiba won't easily go down, but is unfazed since he has more weapons unsheathed.
When the second round began, Juan rushed toward Mashiba and hit him where he isn't guarding while feinting and countering when Mashiba tries to attack. Juan forced Mashiba to the ropes and attacked his guard. The match went in Juan's favour through round four, where he had Mashiba at the ropes again and attacking his guard. Mashiba jumped away from the ropes and turned his body to the side with his guard up, making it difficult for Juan to approach his chest. Juan dodged Mashiba's jabs until he got close enough to get to Mashiba's chest. Mashiba raised his guard, making Juan think he is protecting his jaw while leaving his body open. Juan got closer, however, he was hit by an unexpected right uppercut.
|19||N/A||N/A||200X||Ryō Mashiba||Tokyo, Japan||?(10)||N/A||"World Title Preliminary Match"|
|18||LOSS||17-1-0||200X||Unknown||N/A||?(12)||KO||Second WBA Lightweight Title Defence Match|
|17||WIN||17-0-0||N/A||Unknown||N/A||?(12)||N/A||First WBA Lightweight Title Defence Match|
|16||WIN||16-0-0||N/A||Unknown||N/A||?(12)||N/A||WBA Lightweight Title Match|
|1||WIN||1-0-0||N/A||Unknown||N/A||N/A||N/A||Pro Debut Match|
107-97-10-0 (85 KO)
Juan has a muscular build, straight short black hair with bangs over his forehead and black coloured eyes. He has visible high cheekbones and a trimmed beard along his jawline connected with his moustache. While heading to the ring, he sports a light coloured open robe that has a vertical coloured line from the shoulders down to the bottom on both sides at the front, along with a coloured line that goes from the arm to the hand on both sides. His attire in the ring consists of dark coloured boxing trunks that have a light coloured horizontal line in the middle, multiple promotions on the front, along with light coloured boxing shoes.
Juan is a serious individual and perceptive, analysing the situation while boxing quickly.
Being a former WBA lightweight champion and a hybrid boxer indicates that Juan is a highly skilful boxer that excels at in-fighting and out-boxing. Before a match even begins, he puts off an aura that makes the audience realise he is strong.
Juan has strong punches as noted by then third WBA lightweight ranker Ryō Mashiba, who described even his sloppy punches being strong.< He has notably fast step-in speed.< Juan has a lot of stamina, breathing calmly after being on the offence for an entire first round and is able to fight for twelve rounds.<
Juan rocks his body back and forth before attacking, letting him choose which angle to attack from and making his opponent have to guess where he will come from. He uses exchanges, counting on his strength to win out on them. He favours using his left hook as his knockout punch, as that was used for 80% of his knockouts. His lefts come out in abnormal angles, however, his fist position remains the same. His punches aim both high and low, making it difficult for one to block. He uses a high guard that is higher than his jaw, making it harder to break. He mixes feints with his real punches and moves his head constantly while throwing punches, making it difficult for his opponent to hit him. He is able to break a guard by sending out a punch to the guard and then shove it open. He closes in on opponents without them realising it by throwing a punch while his front leg takes a big step forward, then draws his back leg in after in a single movement, letting him also attack while stepping side-to-side to attack from various angles. He is able to use counters, even while throwing a barrage of punches on an opponent's guard. He is skilful at dodging basic techniques and other techniques such as the Chopping Right. He was able to counter Mashiba's Chopping Right the first time he threw it.
He pressures out-boxers by constantly moving forward like an in-fighter and hitting their guard. He is able to make out-boxers stay along the ropes without even throwing punches and while at the centre of ring by making sudden movements, letting him conserve stamina while pressuring his opponent. While being in close range, Juan can make his opponent try to throw a counter by feinting with a blow above, making him open, to leave his opponent's body open for attacks while they try to throw a counter.
Due to his high guard, he leaves his body open for attacks. Due to his tendency to constantly attack his opponent's body when they guard their head he is more susceptible to uppercuts at close range.