Junkman (ジャンクマン) is a Devil Chojin.
Junkman has slabs of metal covered with spikes in place of his hands. His nickname was Chi no Umi Jigoku (血の海地獄, Hell's Bloodbath). He fought Robin Mask during the Five-Story Ring battle within Warsman's body. Although he was powerful enough to shatter Robin's sapphire-made armour, Robin eventually defeated him with the Reverse Tower Bridge.
It is during a routine fitness test that the Golden Mask and Silver Mask are separated, resulting in all Justice Chojin slowly losing their power.  At this point, a group of Akuma Chojin named the Devil Knights appear with a stolen golden mask.  They reveal that they have sapped the power of all justice chojin, and killed the previous Seven Akuma Chojin, and demand that Kinnikuman defeat them before they restore the Golden Mask to its proper place. 
Warsman is later injured by Planetman, a member of their group, but is in a precarious state.  Terryman decides to turn into a microscopic size and go inside Warsman's body, along with Robin Mask, Brocken Jr., Kinnikuman, and Geronimo.  Terryman decides that the group will hold off the remaining Devil Knights, until Kinnikuman can reach the top floor and retrieve the Golden Mask - the matches will take place on a tower of rings formed along Warsman's spinal column. 
Junkman shows his true form. 
Robin Mask challenged Junkman on the first ring. Junkman sees Kinnikuman scaling the spine, but - as he seeks to stop him from reaching the top - Robin Mask intervenes and stops him from an attack.  Junkman attempts a Junk Crush, but Robin dodges and the attack strikes the spinal column instead. When Junkman tries the same attack again, Robin tries a Shoulder Throw, but he then attacks once more the spinal column. Robin realises the aimed attacks are deliberate: Junkman seeks to disable Warsman and prevent Kinnikuman from climbing higher. 
Junkman tries a Junk Crush again, and Robin allows himself to be caught, before he reveals the philosophy he teaches to younger chojin: "when forced to make a sacrifice, try to save both things".  He thus removes his armour and saves himself from being crushed, as it seemingly stops the Junk Crush.  Junkman crushes the armour and uses it to prove his strength, before he tries to attack Kinnikuman again - Robin stops the attack with his bare hands.  Junkman retaliates by making spikes appear on his front, which violently cut and slash at Robin.
Robin believes he has found Junkman's one weakness, which is that he cannot see what happens at his back, and flips him over, until his front spikes trap him in the ring canvas. He tries a Robin Drop, but Junkman uses his Double Face technique.  Junkman strikes again with a Junk Crush.  Robin refuses to stay down and circles Junkman, only to be hit again, and - in an attempt to gain speed, to avoid being hit following times - removes his belt and part of his helmet.  It appears Robin has used all his strength, even as he gains an advantage and Junkman smashes his face on a corner-post. Junkman uses another Junk Crush, but Robin counters with a Reverse Tower Bridge.
Junkman is thus defeated. 
Perfect Origin Arc
Junkman came back to life during this arc. His only opponent is Perfect Fifth of the Perfect Origin, Painman. They fought in a Steel Cage Deathmatch. Painman's Cushioning Material is a huge pain for Junkman to crush as Painman could simply restore himself even after a powerful Junk Cube Crush. Not even the Junk Spikes could penetrate this almighty Cushioning Material.
After restoring himself, Painman boasts that his Cushioning Material is stronger than Goldman's Diamond Power. Painman's name not only comes from his ability to take on as much pain as he wants, but it also comes from his ability to dish it out as well.
Painman reminisces about his past with Goldman and constantly insults Goldman (now known as Akuma Shogun), angering Junkman since Junkman is one of Akuma Shogun's Devil Knights. Even though Painman couldn't fight Goldman, he's glad to fight Junkman in his place. He adds that Junkman should be proud of fighting him and performed the Terrible Pain Clutch on him.
Junkman manages to escape the Terrible Pain Clutch after motivating himself with a flashback to his training under Akuma Shogun with a Sharpness Junk Upper. Junkman realizes that the heat from his Junk Hands caused the nearby water fountain to heat up. Junkman uses a basic physics rule: air expands if it's heated up. Painman's air bags are no exception to this rule. Thus, Junkman builds up the friction in his Junk Hands in order to set them on fire, so he can create a brand-new variant of the Junk Crush: the Overheat Junk Crush.
Despite piercing one of Painman's airbags, the Overheat Junk Crush exhausts him to the point where he couldn't even lift his Junk Hands. Out of desperation, Junkman amputates himself and boasted that he'll go down in history for popping Painman's airbags. He ends the match with a mighty Junk Crush, crushing Painman between his Junk Hands. Because of his loss, Painman gives Junkman his Wind Dumbbell. Painman orders his men to not attack Junkman because Junkman gave Painman a great fight.
- Slams together his spiked arms onto his opponent. Has a variant used if one of these arms is amputated by any means. He sandwiches his opponent between his attached arm and amputated arm and crushes them.
- Makes a new face appear at the back of his head
- Junkman sprouts spikes from his chest area.
Sharpness Junk Upper
- Junkman bends one of his crusher hands and delivers an uppercut. He used this to escape the Terrible Pain Clutch.
Overheat Junk Crush
- Builds up friction with crusher hands in order to set them on fire. He then crushes his opponent with a mighty Junk Crush.
Win/Loss Record (Singles)
- One of the Six Devil Knights
|General Devil, Satan|
|Seven Devil Chojin|
|Buffaloman, Springman, Atlantis, The Mountain, Mister Khamen, Black Hole, Stereo-Cassette King|
|Six Devil Knight|
|Asuraman, Sunshine, The Ninja, Junkman, Planetman, Sneagator|
|Omega Centauri Six Spears|
|Omegaman Aristera, Hailman, Pirateman, Gear Master, Mariquitaman, Lunaight|
|The Constellation, The Tattooman, Meltdown, Gepparland, Voltman, Ashuraman|