|Dub Name||Jon Yamano / Phantom J|
|Nickname(s)||Masked J (マスクドＪ)|
|Game Debut||Danball Senki (PSP)|
|Anime Debut||Episode 01|
|Appears in||Game, Anime, Manga|
|Voice Actor||Fuminori Komatsu|
|Age||35, 36 (W)|
|Relatives|| Marie Yamano (wife)|
Ban Yamano (Son)
|Occupation||LBX Head Developer and Engineer|
|Affiliation(s)||Seeker, Tiny Orbit, Detector, NICS|
|LBX:|| Masquerade J (as Masked J)|
Achilles Deed (as Detector)
The Empress (Ranking Battle)
Achilles Tank (BOOST Ranking Battle)
Fenrir (W-Call Battle)
O-Legion (W-Ranking Battle)
|Achievement(s)||2050 Artemis Finalist|
Junichirou has brown, messy hair and is akin to an older Ban. He is typically seen wearing glasses and a lab coat. He has noticeable wrinkles on his face due to his age and excessive amounts of LBX research.
Junichirou is a rather unfortunate man - falling into the hands of the Innovators due to his extensive knowledge of LBX. However, his genius was shown to be brilliantly unparalleled. He is shown as an expert hacker, scientist, and inventor; even going as far as to create the Eternal Cycler. Apart from that, he was able to think ahead and gather any necessary information needed to be conveyed when Ban and the others are at lost due to lack of or their current information were vague.
In spite of life favoring him in less than positive positions, he continues to support those with good-will around him, regardless of their intentions, such as his attempts to guide Yagami into realizing Kaidou's selfish ambitions and stopping Lex from consuming to an extremist mentality. He is also aware of people's hidden potential and believes that humans power of unlocking it, hence his faith within Ban and his allies.
As Masked J, Junichirou is more expressive and dramatic, preferring to entertain the audience while closely analyzing his opponents and preparing for a counterattack, even if it means placing himself in an unfavorable position. Masked J also isn't shy of playfully insulting his opponents even though he tends to give advice to help those around him, a testament to Junichirou's true character.
In season 2, Junichiro is revealed to be the man behind Detector. Junichiro expressed regret for how his LBX development created organizations such as Omega Dain. Every "terrorist" act committed was to instill a distrust towards LBX - he believed that the newfound hobby should be eradicated for the world's sake.
In the end, Junichiro was still to blame for the destruction of several cities - however, he claimed to have caused no casualties. Junichiro 'Brainjacked' LBX's in order to further enforce a sense of distrust.
Junichirou was first introduced as deceased in a plane crash 5 years ago prior to the main storyline. In Episode 5, it was revealed that the plane crash was a fabricated report falsified by the Innovators, to kidnap the world's renounced scientists, proving that he is still alive.
Episode 7 explores the plane crash in more detail. He was heading towards the Neo Technology Summit to meet with fellow scientists when the stewardess announces their upcoming destination, confusing him since the flight was expecting to take another ten hours.
In his cell at Kamiya Craft, he greets Yagami with concern for his health. However, he questions his handler on whether or not Kaidou’s methods are indeed beneficial out of curiosity. When Yagami replies, he asks the general another question: is he blind to Kaidou fake mask of justice, or does he know, but refrains from changing his decision.
Ban's flashback in episode 9 reveals he based Achilles on the mythological hero from the book. Ban claims Achilles should be invincible but Junichirou points out even Achilles had a weakness.
The Seekers attempted to rescue him from Yoshimitsu Kaidou's mansion in Episode 15, only to be kidnapped and Kaidou has the professor brought in. Just as Yoshmitisu is about to have everyone killed, Professor Yamano laughs and reveals that even if Yoshimitsu has Achilles, it does him no good. He reveals that he hid the decoder for the Platinum Capsule inside the Methanus GX as the prize for the Artemis Tournament without Omega Dain's knowing. The only way to use its technology is to have both together at the same time. Professor Yamano then uses his glasses and triggers some explosives hidden in Yoshimitsu's house, allowing the crew to escape. Ban tries to reach his father, but Professor Yamano heads off in a different direction, saying he has some other business to take care of.
After the Seeker's "failed" mission, Junichirou escapes separately from the Seekers under alternative actions to assist Ban and the others. He was seen entering the Artemis Tournament, disguising himself as a participant player named Masked J. Using his handmade LBX, Masquerade J to win through the B block finals. Masquerade J makes the finals of B Block, battling Shou Kanzaki. In a short time, Kanzaki’s Gladiator places him on the defensive and forces Masquerade’s health below 25%. However, he memorized Kanzaki’s patterns and received attacks on purpose. With that swiftly dodges attacks like in a masquerade dance performance. In a few hits, Masquerade strikes Gladiator down and knocks him into a wall. He finishes Shou with his hissatsu function: Storm Sword. As Shou collapse his failure, he advises Shou to work on his defense in order to improve his offensive potential, but falls on deaf ears as calling the kid “boy” drove him away in anger. Regardless, he gives the amazed audience a bow and moves onto to the finals.However Masquerade J was eventually destroyed by Yuuya's Judge to protect Ban's Achilles. Before his LBX become break over, he managed to mail to his son the LBX Odin data, thus completing his mission.
After 3 days of the incident of Artemis, Ban, Ami and Kazuya had known his true identity thanks to Yuusuke Uzaki. Then, Tiny Orbit analyzed the LBX Odin data from the retrieved Platinum Capsule, following Junichirou's next instructions to materialize through the plans as the capsule's second housing LBX. Later, after the speeding Linear Motor incident, Ban finds out that his father inputted voice instructions into Odin, explaining how to retrieve the Metanus GX from the Infinity Net. When Odin and Hunter were fighting Hades, he gave the LBX Fenrir data to Hunter and Otacross saves Fenrir's data and sent it to Tiny Orbit to fabricating.
When Lex turns on the Seekers, Junichirou arrives, persuading Lex as the Professor told him that Hiyama left his hatred get the better of him in the end.
In Danball Senki W, it was revealed that he was the masked man behind Detector, to battle against Omega Dain. Once his identity is uncovered, he teams up with Ban to defeat Gardyne and dismantle Paradise. However, he's warned by Owen Kaios that he will face punishment for his actions after Omega Dain is defeated.
- In the game, Junichirou wears a lab coat embedded with the words L5, for Level-5, the maker logo of the Danball Senki series.
- His name is similar to Yuichiro Hikari of Rockman.EXE's Series, both have the hope in his son to fight against evil.