|Dub Name||Jon Yamano|
|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 wears glasses and a lab coat.
Usually shown with a stern and serious appearance, his facial features reflect the many years he has been doing LBX research.
Junichirou is a poor guy with honest intentions, who cares about everything else all the while to support his family. His genius was shown to be brilliantly unparalleled throughout the Danball Senki storyline when he developed the LBX technology, the Eternal Cycler, excellent computer expertise, and clever tactician to consider the most remote possibilities many steps ahead.
After revealing himself as being the Detector masked mastermind, his honesty was clearly expressed from his nobility and regretfulness for how his LBX development introduced Omega Dain in the first place. Every "terrorist" act commited, it was to carry the burden of his LBX technology while believing the newfound hobby should be eradicated for the world's sake. It was proven as the Detector's actions showed no injury or harm for brainjacking LBXs as to only scare civilians, as well surprised for he never anticipated for the Cairo Hotel Computer to overload in the process.
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.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, Masquarade J to win through the finals but was eventually destroyed by Yuuya's Judge. Before his LBX was break over, he managed to mial 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. 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 Metanasu 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.
- 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.