|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.
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.
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. However Masquerade J was eventually destroyed by Yuuya's Judge. Before his LBX was 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 and he tells Lex that he 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.