Wolfman is a Japanese Sumo Chojin who once held the title of Chojin Sumo Yokozuna, but later switched to Chojin Wrestling. He trains his muscles vigorously and boasts of his Beautiful Muscles of Steel (鋼の肉体美 Hagane no Nikutai-bi), muscles that exceed Kinnikuman's. At first he despises Kinnikuman and calls him Zeinikuman (ゼイ肉マン, Flabbyman), but after losing to him in a Sumo match he begins to respect his abilities. From then on he appears as an Idol Chojin and fights against the Akuma Chojin.
With the 21st Chojin Olympics final preliminary and his fight with Springman, Wolfman often ends up facing rather plain opponents in one-sided fights. He becomes the cannon fodder, or jobber, of the Justice Chojin (quickly and easily defeated in order to show off how powerful the villains are), dying and returning to life three times throughout the series. Despite the poor treatment of his character, Wolfman's speciality in Japan's national sport of Sumo has garnered him plenty of fans.
Wolfman first debuts during the 21st Chojin Olympics. He challenges Kinnikuman for the right to be Japan's representative and a fierce rivalry ensues. However, when they both end up nearly disqualified during the final prelim, they call a truce and work together as a single Japanese Representative. They both make it into the tournament, but Wolfman gets a bye into the Second Round where he fights and defeats Cubeman. In the semi-finals he faces Kinnikuman in a sumo match. Wolfman nearly wins, but at the last second Kinnikuman reverses Wolfman's toss into a Kannuki Suplex.
Wolfman later shows up with Terryman, Robin Mask, Warsman, and Brocken Jr. to aid Kinnikuman during the Seven Akuma Chojin Arc. He goes up against Springman, a living spring, in a match taking place in the Tottori sand dunes. Wolfman's great strength give him an advantage for a little while, but Springman eventually tears him apart with his Devil Slinky technique. He is later revived along with Robin and Warsman by a dying Buffaloman.
Wolfman appears again during the Golden Mask Arc, but dies after offering up his life-force so that a recently killed Kinnikuman can live again. Before he dies, he has Geronimo cut of his danbatsushiki as a symbol of his friendship for Kinnikuman. He and Geronimo are later revived by the Perfect Mask, and Wolfman teams up with Brocken Jr. for the Dream Tag Tournament. Unfortunately, before their first match (against Mongolman and Buffaloman) is interrupted by Kendaman and Screw Kid, who take him and Brocken out with their Hellish Screw technique. Wolfman is seen again when he and Brocken help Kinnikuman and Kinnikuman Great fight off reporters trying to get a picture of an unmasked Robin Mask, after that, however, he is referred to as being dead and his soul shows up with the souls of other fallen comrades to help Kinnikuman during the fight with the Hell Missionaries.
Without any explanation, Wolfman comes back to life and moves to Hawaii, where he has a successful career as a make-up wrestler. But, when Neptuneman sends out his message to all Justice Chojin in the world to come to Osaka and support Kinnikuman during his fight with Kinnikuman Super Phoenix, he and Jesse Maivia head for the airport together. They both show up (with Terryman and Ramenman) in time to stop the Evil Gods from attacking Super Phoenix's mother.
After the Survivor Match has passed, Wolfman has decided to retire from sumo wrestling because his tendon can't be repaired at all. His doctor notes that the tendon in the left leg went past the limit for surgeries and suggests that Wolfman should become a stable master. 
During the retirement ceremony, his friends and family all take a shot at cutting Wolfman's topknot. Cubeman even shows some respect towards the man who defeated him in the 21st Chojin Olympics. Meat cries because Wolfman is the second friend to retire. Geronimo recalls the time he had to cut Wolfman's topknot during the Golden Mask arc and says that this is his second time doing this. Geronimo also praises Wolfman and calls him an unsung hero. Kani Base screws up the haircut ritual, but Coyoteman slaps him and ends the ritual with a grand recovery. Mayumi hands Wolfman a trophy commemorating his service as a Chojin Sumo Wrestler. 
Black Ship interrupts the retirement ceremony, while carrying a battered Canadianman and Specialman . Meat tries to defend Wolfman, but he gets beaten up by Black Ship. Enraged by Black Ship, Wolfman challenges him to one last sumo match. Before the match begins, Geronimo tosses Wolfman's top knot back at him, giving him the strength to take on the American sumo wrestler. Despite having the advantage during the match, Black Ship loses to Wolfman because of a combination of Wolfman's Friendship Power and the Gasshō Hineri. 
In Kinnikuman Nisei, Wolfman has gained some weight and become a teacher at the Hercules Factory. He appeared at ringside along with Buffaloman and Jesse Maivia during Kinniku Mantaro's fight with Scarface but has yet to play an important role.
- Wolfman repeatedly slaps his opponent's face until it swells up to look like a Rubik's Cube (ironically first used on Cubeman, whose face looks like a Rubik's Cube already).
Wolfman Slap (ウルフマン張り手, Urufuman Harite)
Gasshō Hineri (合掌ひねり)
- Wolfman's most well known finishing move. He flings the opponent into the air either by their head or by their neck.
- He claps his hand in front of his enemy's face to disorient them.
Body Slam (ボディスラム)
- Wolfman lifts his opponent and slams them into the ground.
Izori Throw (居反り投げ, Izori Nage)
- Wolfman dives towards his opponents' leg, grabs it and pulls them up.
Shiranui Unryū Nage (不知火・雲竜投げ)
Speech & Quotes
He uses phrases like Dosuko~i! (どすこーい！) and Gottan desu! (ごっつぁんです！)
Win/Loss Record (Singles)
- O Cubeman (Rubik's Cube Twist→ Gasshō Hineri)
- X Kinnikuman (Kannuki Suplex)
- X Springman (Devil Slinky)
- O God of Brute Strength (Izori Nage)
- X Kinnikuman (Ring Out)
- O Black Ship (Gasshō Hineri)
- O Lunaight (Shiranui - Unryuu Nage)
- X Clioneman (???)
Win/Loss Record (Tag)
Win/Loss Record (Anime Only)
- O Harigorasu (Abise Taoshi)
- X Black Sumoman (Body Splash)
- O Black Sumo (Gasshō Hineri)
- O Haniwa Satan (Gasshō Hineri)
- Δ Haniwa Satan (Rubik's Cube Twist)
- O Hydra Sumo
- Δ The Sanzokun (Body Slam) (Tag Match with Brocken Jr.)
- X Terryman (Popularity Contest)
- Theme Song: "Dohyō Hero (土俵の英雄, Dohyō no Eiyū)" by Akira Kushida
- Wolfman was modelled after popular rikishi Chiyonofuji Mitsug,"Wolf" being Chiyonofuji's nickname
- In the anime he is renamed Rikishiman
- He is renamed Sosumi in the Ultimate Muscle English dub.