- Name: Mayumi Kinniku (キン肉真弓 Kinniku Mayumi)
- AKA: King Kinniku (キン肉大王 Kinniku Daiō)
- Classification: Seigi Chojin
- Homeland: Planet Kinniku
- Age: 65, 100 (Nisei)
- Height: 193 cm
- Weight: 115 kg
- Chojin Kyodo: 650,000 Power
- Favorite Techniques: Iron Claw, Kinniku Flash
- First Appearance: Manga Chapter 3, Anime Episode 1
Mayumi Kinniku is the father of Ataru and Suguru Kinniku and the 57th King of Planet Kinniku. He has the character 王 (Ō) written on his forehead. He is a former Chojin Olympic V2 Champion as well as a Universal Grappling Champion. He has a fierce and long-standing rivalry with Harabote Muscle (the future chairman of the Chojin League), and the two of them frequently appear in Exhibition Matches which are unpopular with the younger fans.
He is married to Sayuri Kinniku, and although she is embarrassed by how he sometimes behaves, the two are very much in love with one another. Much to her annoyance, the only food he knows how to cook is curry. Despite being a descendant of the Royal Kinniku Family (キン肉王家, Kinniku Ouke), he does not know any of the 3 Great Secrets of the Kinniku Clan and never uses the Face Flash.
Because strict training caused his eldest son Ataru to run away, he raises his second son Suguru very indulgently. However, frequently quarreling with Suguru, wanting to strangle his neck as a child because of his stupid face, and mistaking him for a pig and subsequently abandoning him on Earth are just a few of the examples of how Mayumi fails as a father. Nonetheless, whenever Suguru fights, and especially when he's winning, Mayumi cheers loudly for him and brags that he's his son.
His name comes from Akinobu Mayumi.
- Kazuhiko Kishino in Kinnikuman
- Nana Yamaguchi (young; ep44)
- Masaharu Sato in Kinnikuman: Scramble for the Throne
- Kozo Shioya in Kinnikuman Nisei
- Jimmy Zoppi in Ultimate Muscle (English Dub)
Mayumi was born to Tatsunori Kinniku, the 56th King of Planet Kinniku and inventor of the Niku
Curtain. Other than a fierce and long-standing rivalry with Harabote Muscle, no major accomplishments of his are ever mentioned, and how he ever became king is unknown. After becoming king he marries Sayuri Kinniku and the two eventually have a son named Ataru and years later another one named Suguru. When Sayuri is still pregnant with Suguru, Ataru runs away from home after learning that he will not be the one to become king. While vacationing on Earth, Mayumi mistakes a pig for baby Suguru and leaves him behind. The pig, King Tōn, grows up as prince in Suguru's place and overthrows Mayumi.
Mayumi then sends Meat to Earth to retrieve Suguru, so he can defeat Tōn and take the throne. However, Suguru turns out to be a goofy failure and loses. Fortunately, the chef that once owned Tōn arrives to reclaim him, giving Mayumi a chance to snatch the King's Belt back when nobody is looking and reclaim the throne. He then has Meat take Suguru back to Earth in order to train him.
Mayumi continues to loudly support his son throughout the series and is one of the most prominent supporting cast members. During the Survivor Match for the Kinniku Throne Mayumi reveals that he is much more intelligent than he seems to be when he frequently interprets the passages in the Muscle Prophecy Book.
Mayumi has had a reletively small role in Nisei, appearing only in the first few chapters (where it seems his wife Kinniku Sayuri has died) and the current storyline. He has pretty much the same relationship with Mantarou that he did with Suguru. In the current storyline (a Tag Tournament in the past), he and Harabote have resumed their roles as main supporting characters.
- Birthdate: 1914
- Family: Tatsunori (father), Nemesis (uncle), Sayuri (wife), Ataru (son), Suguru (son), Bibimba (daughter-in-law), Mantaro (grandson)
- Theme Song: "Glorious King (栄光の大王, Eikō no Daiō)" by Masanori Sato
- 9th Chōjin Olympic Champion
- 10th Chōjin Olympic Champion
- 11th Chōjin Olympic Runner Up
- Intergalactic Choujin Heaviweight
- Intergalactic Grappling Champion
- 1st Kinnikuman Nisei ~All Choujin Dai Shingeki~ Popularity Contest (58th Place)
- 57th King of Planet Kinniku
- Mayumi-chan (真弓ちゃん) (Harabote Muscle)
- Anata (あなた, Dear) (Sayuri Kinniku)
- "Hanshin" Mayumi (阪神の真弓, Hanshin no Mayumi) (Self-Calling)
- "Crewcut" Ittetsu Hoshi (角刈りの星一徹, Kakugari no Hoshi Ittetsu) (Self-Calling)
- "Buzz cut" Ittetsu Hoshi (二枚刈りの星一徹, Nimaigari no Hoshi Ittetsu) (Self-Calling)
- Win/Loss Record
- X Harabote Muscle
- X King Ton
- O Harabote Muscle (Figure 4 Leg Lock)
- Δ Harabote Muscle (Iron Claw)
- Δ Harabote Muscle (Killer Key Lock)
Prince of Planet Kinniku
King of Planet Kinniku
- Preceded by: Unknown
- Followed by: himself
Choujin Olympics Champion (10th)
- Preceded by: himself
- Followed by: Harabote Muscle
Choujin Olympics Runner Up (11th)
- Preceded by: Unknown
- Followed by: Unknown