- Classification: Perfect Choujin
- Homeland: United Kingdom
- Age: 26, 27 (Throne arc), 61 (Nisei)
- Height: 240cm
- Weight: 210kg
- Choujin Kyoudo: 28,000,000 Power
- Trademark Techniques: Quarrel Bomber, Quarrel Special, Double Leg Suplex
- Tag Teams: Hell Missionaries (Big the Budou), Ganryu Island Combo (Kinnikuman), Hell Expansions (Seiuchin), Hell Expansions Nouveau (Mammothman)
- First Appearance: Manga Chapter 209 ("Graydar" disguise) and 218 (Neptuneman)
- Kishino Kazuhiko in Kinnikuman
- Yukitoshi Hori in Kinnikuman: Scramble for the Throne
- Eiji Takemoto in Kinnikuman Generations (PS2) and Muscle Generations (PSP)
- Neptune Mask (ネプチューンマスク?)
- The source of Neptuneman's Magnet Power. It takes magnetic energy from The Earth itself and transfers it to Neptuneman's body. Locking a magic keyhole in the Earth's crust is the only way to turn the mask off.
- Quarrel Bomber (喧嘩（クォーラル）ボンバー?)
- First used on Warsman during the fight with the Choujin Master/Student Combo. It is a simple Axe Bomber-style clothesline. As The Samurai he referred to it as the Iai-Giri Bomber (居合い斬りボンバー, Iai Giri Bonbaa?).
- Quarrel Special (喧嘩（クォーラル）スペシャル?)
- First used on Kendaman. A variation of the Manji Hold which sees the attacker wraps his leg around the victims neck while pulling on their left arm with both hands.
- Double Leg Suplex (ダブル・レッグ・スープレックス?)
- First used on Warsman during the fight with the Choujin Master/Student Combo. Neptuneman grabs an opponent from behind, piercing their back with the spikes on his vest. He then places his hands under their thighs, bends back, and drives them shoulder-first into the canvas.
- Judgement Lock-Up (審判のロックアップ, Shinpan no Rokku Appu?)
- Neptune Sliding (ネプチューン・スライディング?)
- Magnetic Storm Driver (磁気嵐ドライバー, Jiki Arashi Doraibā?)
- First used during the fight with the 20 Million Powers. A powerbomb move in which the Magnet Power draws the opponent towards the canvas.
- Demonic Descent (魔の直滑降, Ma no Chokkakkou?)
- First used during the fight with the Muscle Brothers. A super powerful version of the common back toss.
- Chicken Wing Clutch (鶏の羽交い締め, Niwatori no Hagai Jime?)
- Used as The Samurai. From behind, Neptuneman hooks one arm with one of the opponent's arms behind their back and then places his other arm around their face. He then holds his hands together for a deadly choke.
- Quarrel Ride (喧嘩（クォーラル）ライド?)
- Cross Bomber (クロス・ボンバー?)
- The trademark technique of the Hell Missionaries. First used on Warsman during the fight with the Choujin Master/Student Combo. Two simultaneous Quarrel Bombers on a single opponent, Neptuneman from the front and Big the Budou from behind. It is strong enough to knock an opponent's mask off. He also does this technique with Kinnikuman.
- Cross Enzui (クロス延髄?)
- A Kinnikuman Nisei technique done with Seiuchin. Large optical fibers protrude from Neptuneman's arm and attach themselves to the opponent's back, while Seiuchin does the same from the front with one of his tusks, holding the opponent in place. They then perform an explosive Cross Bomber. The result of this technique is that the skin on the opponent's face is knocked off.
- Magnetic Storm Crash (磁気嵐クラッシュ, Jiki Arashi Kurasshu?)
- A tag technique first used during the fight with the 20 Million Powers. A Magnet Power technique where Budou performs a Magnetic Storm Driver on one opponent from above and Neptuneman does one on the other opponent from the ring, causing both opponent's heads to eventually collide with one another.
- Mask The End (マスク・ジ・エンド?)
- A tag technique used during the fight with the Machineguns. A Magnet Power technique where both Neptuneman and Budou launch themselves in a dropkick position towards opposite sides of an opponents head. They then begin spinning around, causing the opponent's mask to peel off (in a similar manner that you would peel an apple).
- Hell's Triple Sentence (地獄の三実刑, Jigoku no San Juukei?)
- A tag techniques used during the fight with the Machineguns. Neptuneman performs a Sleeper Suplex on an opponent, then spins the mask around backwards, and finally Budou hits the opponent with a Body Splash.
- Ganryu Island Drop (巌流島ドロップ, Ganryu Shima Doroppu?)
- Used during the fight with Super Phoenix and The Omegaman. With the opponent upside down and falling towards the ring, Neptuneman and Kinnikuman jumps towards him. Neptuneman, with his back to the opponent's front, hooks his arms around the opponent's legs while Kinnikuman, facing back to back with the opponent, hooks his arms with the opponent's arms. They then drive him headfirst into the canvas.
- Rainbow Bridge Suplex (レインボーブリッジスープレックス?)
- A tag technique used during the fight with Super Phoenix and The Omegaman. While back-to-back and in midair, Neptuneman and Kinnikuman each take an opponent and perform a Back Drop, causing their heads to collide with one another.
Neptuneman's true name is Kenkaman (喧嘩男 Quarrelman?), (he was also called Street Scrapper in the US), and he is a Perfect Choujin from England. He was an incredibly powerful wrestler, so much so that he found it impossible to find opponents who could challenge him. Kenkaman even told Robin Mask that he (Robin) was too weak to fight him. He tried to end his life by jumping into the River Thames, but in doing so found the place where Neptune King, another Perfect Choujin, had been in hibernation. Neptune King had escaped from the world years ago after Choujin Wrestling began to become less about battle and more about tournaments. He longed for the days of Death Matches, which Kenkaman found fascinating. Neptune King gave Kenkaman the Neptune Mask and rechristened him Neptuneman, and he himself wore a mask and became Big the Budo. Both masks gave them Magnet Power (transferred straight from The Earth itself) and increased their strength many fold. (more to come)
Dream Choujin Tag Arc
Neptuneman and Big the Budo entered the Universal Tag-Team Tournament as the Hell Missionaries, planning to defeat and steal the masks of the chojin competitors. Then, they would give the masks to Big the Budo's henchmen, so that 'Kinnikuman' and 'Robin Mask' would be working for them. Meanwhile, the henchmen were flying on their way to Earth...all 1,000 of them. The Hell Misionaries disguised themselves during the preliminaries, revealing themselves to punish Screw Kid and Kendaman for losing to the 20 Million Powers(Mongolman/Buffaloman). In the first round of the finals, the Hell Misionaries fought the Master/Student Chojin Combo, Warsman and Robin Mask, the latter of whom recognized Neptuneman for who he was (or used to be). The match ended with Warsman dead, and both of them unmasked by the Hell Misionaries' Cross Bomber move. in the second round, the Hell Missionaries went up against the 20 Million Powers, and the match ended in the Perfect Chojin's favor, with Mongolman unmasked and revealed to be Ramenman. In the final match, the fight was held in a three round 'Sword-floor' deathmatch Big the Budo designed against the Muscle Brothers, Kinnikuman and Kinnikuman Great. Though the first round ended in the Hell Missionaries' favor, with Great revealed to be Terryman, the victory ultimately went to the Machine Guns when Budo began using the swords from the 'Sword-floor' deathmatch. The use of weapons was against the rules of the Perfect Chojin, and Neptuneman turned on his mentor for doing so. After the fight, Neptuneman flew into the sky and self-destructed, signaling for the Perfect Chojin army to retreat.
Survivor Match for the Kinniku Throne
With the help of his Perfect Choujins, Neptuneman is revived illegally and escapes from the Choujin Graveyard. He arrives at the end of the Team Super Phoenix vs. Team Soldier battle and collects the ashes of Ataru Kinniku. He then hides in the bamboo forest in Nara Prefecture where Warsman is training and helps him in his fight against Mammothman with advice. He appears again in the shadows during Geronimo's match against The Omegaman and saves him from the Omega Catastrophe Drop by blowing some of Ataru's ashes into the ring. When he tries it a second time, Geronimo refuses his help, fearing that Omegaman and the Choujin Enma would learn his true identity. He returns as The Samurai to help Kinnikuman and Robin Mask in a 3-man tag match against Kinnikuman Super Phoenix, Omegaman, and Mammothman. When the Samurai's Muscle Prophecy page is burnt his costume goes away and he is changed back into Neptuneman. Super Phoenix eventually ties him up underneath the string connected to his real page and places a candle on his back. He breaks free anyway, breaking the string and burning his page, in order to take Kinnikuman's place in the Omega Catastrophe Drop, after which he disappears. His soul then helps Robin, Ataru, and Gero free Kinnikuman's Kajiba no Kuso Dijkara and defeat Super Phoenix. The four of them are later revived by Kinnikuman's Face Flash.
For over 30 years Neptuneman lived in England in peace as Quarrelman. But after the Time Chojin attack, he returns to active duty as Neptuneman and sneaks aboard the H.M.S. Kevin Mask timeship with Mantaro and the New Generation. Neptuneman stunned everyone by choosing mild-mannered Seiuchin as his tag partner. Neptuneman had remembered the story of The Walrus and the Carpenter from his homeland and decided to train Seiuchin to bring out the untapped cold-blooded power in him, transforming him into a violent beast. As "The Hell Expansions", the two of them are collecting the skin off of their opponent's faces instead of masks.
This was until the team faced off against the "Hell's Bears", which consisted of Belmond (Warsman) and Michael (Mammothman). Seiuchin fought Mammothman, and in the middle of the match, returned to his senses and betrays Neptuneman. However, Mammothman betrays Warsman and sides with Neptuneman, which leads to both of them knocking off Seiuchin's face with a Optical Fiber Cross Bomber and defeating Warsman.
Before the semi-finals, Satan appears, and Neptuneman and Mammothman reveal their apparent alliance with the Jikan Choujin Thunder and Lightning, throwing a spider spawned by Satan at Suguru, which enters his chest and forms into an hourglass.
- Alias: Quarrelman, The Samurai
- Favorite Food: Barbecue Beef
- Theme Song: "Uncrowned Emperor (無冠の帝王, Mukan no Teiou?)" by Norimasa Yamanaka
- Submitted by: Hiroo Shibata (柴田浩暢) of Aomori Prefecture as "Ichiban Mask".
- his "Hulk Machine" vest was submitted by Hirosube Naka (中宏術) of Osaka.
- "Graydar" disguise submitted by: Koji Nishikawa (西川興治) of Miyagi
- The Samurai submitted by: Katsuaki Nomiya (野宮勝昭) of Tokyo.
- Championships (Kenkaman era)
- Universal Choujin Glima Top-Rank Champion ('73)
- England Choujin Premium League Champion ('77)
- Choujin Olympic English Qualifying Champion ('79)
- Team Kinnikuman (Finals) (Position never revealed)
- Win/Loss Record (Singles)
- O 541 Unknown Opponents (KO)
- X Robin Mask (Forfeit) as Quarrelman
- O Kendaman (Quarrel Special)
- O Sunshine (Double Leg Suplex)
- X The Omegaman (Omega Catastrophe Drop)
- Win/Loss Record (Tag)
- Hell Missionaries (Big the Budou)
- O Choujin Master/Student Combo (Cross Bomber)
- O 20 Million Powers (Cross Bomber)
- O Muscle Brothers [Round 1] (Cross Bomber)
- X The Machineguns [Round 2] (Muscle Docking)
- X The Machineguns [Round 3] (KO)
- Hell Expansions (Seiuchin)
- O Check Mate (Cross Bomber)
- Δ Muscle Brothers Nouveau (Interference from Fireball - Flying Fogey Squad)
- O Fireball - Flying Fogey Squad (Optical Fiber Cross Bomber)
- O Super Trinities (Optical Fiber Cross Bomber)
- O Hell's Bears (Back Drop- Warsman)