Buffaloman was originally a 1,000,000 strength choujin who was continually beaten because he lacked skill. He eventually met and struck a deal with Satan, who gave him more Choujin power whenever he killed another choujin. Eventually he killed so many that his power had climbed to 10,000,000. He and his comrades, all known as the Seven Devil Choujin (Springman, Atlantis, SteCassette King, Black Hole, Mr. Kamen, and The Mountain), were eventually captured by a grouping of 100,000 seigi choujin (justice supermen) and space police and trapped in a space station. This station was accidentally opened when Kinnikuman was thrown straight onto the release mechanism by overenthusiastic fans.
Buffaloman and the other Devil Choujin arrived at the scene where Kinnikuman and his friends were celebrating the conclusion of the 21st Choujin Olympics. Desiring to see how strong today's choujin heroes were, Buffaloman split Alexandria Meat's body into seven pieces so as to force Kinnikuman to beat them all in 10 days if he wanted to save his friend. When Kinnikuman was too injured to keep fighting the Seven Devils after he had beaten SteCassette King and Black Hole, his friends stepped in to take on the remaining Devil Choujin in his place, and Buffaloman was pitted against Warsman. Warsman was constantly stymied by Buffaloman's superior power, and although he managed to break off one of Buffaloman's longhorns, he was killed in the end.
Buffaloman faced Kinnikuman in a double match with Springman in the final match of the story arc. Despite it being called a tagteam match, Buffaloman's attention was focused exclusively on Kinnikuman while Springman fought and lost to Mongolman. Buffaloman was an extremely tough opponent, using his power to reverse Kinnikuman's trademark finishing move, the Kinniku Buster, but lost control of his power when he absorbed Kinnikuman's Kajiba no Kuso Chikara (Burning Inner Strength). Because of the respect Kinnikuman showed him even though they were mortal enemies, Buffaloman changed sides at the end of the match and vowed to join the seigi choujin if he survived his punishment for defeat. He was fatally injured by the devil, but before he died gave up his Choujin Power, bought with the blood of other herores, to bring Warsman, Robin Mask and Wolfman, who had died fighting his teammates, back to life.
He appeared again during the Golden Mask arc in Ashuraman's corner during Kinnikuman's fight with him, but turned on Ashuraman and became a good guy for the remainder of the series. He then faced the Devil Knights leader, Akuma Shogun, in order to give Kinnikuman more time to perfect the Kinniku Driver. He was eventually defeated by Akuma Shogun's Hell's Guillotine technique. During the fight between Akuma Shogun and Kinnikuman, Shogun began to revive the Devil Knights and absorb them to become more powerful. But Buffaloman put on Shogun's mask/head and fought them off, giving Kinnikuman the chance he needed to defeat Shogun with the Kinniku Driver.
Buffaloman returned as Mongolman's partner in the Dream Tag Tournament, forming the 20 Million Powers. The name of their combo came from Buffaloman's 10,000,000 power and Mongolman's 10,000,000 techniques (10 Million+10 Million). Their first match was to be against the Most Dangerous Combo (Brocken Jr. and Wolfman), but the match was interrupted when Screw Kid and Kendaman arrived and took out the Most Dangerous Combo. This resulted in the 20 Million Powers fighting the Perfect Choujins instead. The match began with a fierce one-on-one battle between Buffaloman and Kendaman, but Buffaloman eventually took them both out with his Hurricane Mixer. Fearing the punishment that comes from failing their Boss, Screw Kid and Kendaman begins using dirty tactics. In the end, the 20 Million Powers were able to defeat them with their Long Horn Train technique. For losing, Screw Kid and Kendaman were destroyed by their bosses, the Hell Missionaries (Neptuneman and Big the Budou).
In the next round, Buffaloman and Mongolman faced the Hell Missionaries themselves. Though they tried their best, Neptuneman and Budou made short work of them with their Magnet Power. The 20 Million Powers refused to give up, however, and tried their Long Horn technique again. Unfortunately, the Hell Missionaries were able to defeat it. The match ended with Mongolman being unmasked and revealed to be Ramenman after being hit with the Cross Bomber.
Later, Buffaloman donated the last of his Long Horns to Doctor Bombay so Bombay could repair Kinnikuman's severed arm.
When Kinnikuman's right to the Kinniku Throne was challenged by five pretenders to the throne, Buffaloman (along with Brocken, Ashuraman, and The Ninja) surprised everyone joining Team Soldier. Buffaloman, without his Long Horns, took part in only one fight.
In the final match during the semi-finals battle against Team Super Phoenix and Team Soldier, Soldier, Buffaloman, and Brocken competed in a 6-Man Tag Match against Super Phoenix, Mammothman, and Prisman. The match took place in a floating multi-sided ring. Buffaloman, for the most part, fought against Mammothman. Tremendously weaker without his Long Horns, he found himself losing against the nearly unstoppable Mammothman. He was finally able to gain and advantage when Kinnikuman returned the Long Horns used to fix his arm before the Tag match finals. Soon after, Brocken took out Prisman, but then fell into the canyon below and died. Seeing how much Soldier and Buffaloman cared for their fallen comrade convinced Super Phoenix that Soldier wasn't the real Soldier.
As Soldier begins to have his true identity figured out by his own father Mayumi as his long-lost elder son Ataru, the Evil Gods choose to sabotage him to eliminate him and help Phoenix win the tournament. The God of Brutality steals a page from the Muscle Prophecy, a book owned by Kinniku Clan royalty which contains past, present, and even future information on every Choujin ever, as a means to reveal who Soldier is to Super Phoenix. As the God of Brutality attempts to give the page to Super Phoenix via Mammothman, Buffaloman sees a vision of Mayumi in his head, forcing him to take the page to protect it. As the mammoth Choujin prepares to hand it to Phoenix, the bull Choujin performs the Choujin Cross Drop on him, jumping out of the ring and forcing Buffaloman to hold the page in his mouth. As they fall, Mammothman hits Buffaloman with his Nose Fencing technique and retains the page. At the last second, Buffaloman hits Mammothman with a Buffalo Bomb on the roof of the Himeji/Nagoya castle and saves the page again.
The Evil Gods then arrived and began attacking the floating ring in an attempt to take out Ataru. As the ring fell, Buffaloman caught it and held it up. Weakened from the battle with Mammothman, he put on a red headband given to him by the other Seigi Choujins and found enough strentgh to not only hold the ring up longer but also remove his arm guards and toss them up to Ataru. He then pushed it into the air and as it fell again, he jumped up and hit it with a Hurricane Mixer, successfully putting it back in mid-air. Unfortunately, Buffaloman had no more strength and fell into the canyon below. He is revived (along with his teammates) after the tournament by Kinnikuman's Face Flash.
In Kinnikuman Nisei, Buffaloman is a trainer at the Hercules Factory. He fought and was defeated by both Terry the Kid andJade in their graduation matches. He is involved in the current storyline (a Tag Tournament in the past), once again teamed with Mongolman as the 20 Million Powers.