Royal Kinniku Family
According to an organization chart shown by Meat to Kinnikuman in the earliest chapters of the manga, the Kinniku Clan was always meant to have the greatest influence over other groups of super-heroes.
With the format of the manga being retooled from a superhero comedy to a wrestling manga revolving about Chojin, the Kinniku Clan was also retooled as the most influential clan in the whole Chojin Association, overseers of the Hercules Factory and directly responsible for the Chojin Olympics and every form of organization for the Seigi Chojin.
Primus inter pares in the Kinniku Clan is the Kinniku Royal Family, whose blood descends directly from Silverman, the former Perfect Chojin wishing to rediscover the mercy that Strong the Budo lost when he stopped being the Merciful God and became The Man.
After his legendary fight with Goldman and the loss of his physical body, he entrusted his whole clan, and specially the Royal Family, with the task to rediscover the value of mercy and friendship and perfect the Muscle Spark in a move highlighting those ideals.
While mostly every memember of the Kinniku Clan is meant to be strong and kind, the Royal Family has powers beyond even their imagination.
The Royal Family is made of masked fighters, with various mask inspired by the one once worn by Silverman himself, in those times being called Musman, with Mus being part of a portmanteu with the Greek word for Muscleman: once a prince of the Kinniku Clan is unmasked, he has to take his own life or face execution. However, the english version of the anime and manga censor that fate in becoming a complete unperson, forced to forfeit his royal status and forbidden to fight as a wrestler or a chojin for the rest of his life, expelled and reviled from the Kinniku Clan.
That weird custom comes with some powers: the most talented members of the royal families have access to the elusive Face Flash, and when they choose to show part of their faces, they can emit a ray of pure chojin energy with positive effects, from the ability to heal every injury to the ability to protect friends and clean polluted water.
When a King of the Kinniku Family feels himself dying of old age, he istinctively seeks the Muscle Falls, a gigantic graveyard surrounded by a river to die: only the Royal Family is allowed to drink and bathe in those sacred waters, but if a commoneer manages to do so, he'll receive the ability to use the Face Flash too, along with the blessing of the kings.
Until the lineage is broken, the heirs of the Royal Family able to understand the ideals of mercy share access to the Kajiba no Kuso Djikara, the Ultimate Power, or the Burning Inner Strengh, closesly tied to Mercy and Friendship enhancing their powers beyond their physical limitations.
Those power are latent and need to be awakened, as Mayumi Kinniku never managed to use the Face Flash nor the Kajiba no Kuso Djikara, Kinnikuman had to learn the extent of both and Mantaro Kinniku, despite being able to use the Kajiba no Kuso Djikara since his early teens when under duress, never exibited the ability to perform the Face Flash and had to be schooled by his uncle into using the Burning Inner Strengh at his intended output.
While the Royal Family was always the embodiement of the ideals preached by Silverman the Kinniku Clan had a dark history by himself.
Resisting to the ideals of mercy spread by Tatsunori Kinniku, some ministers of the Kinniku Clan rebelled and tried to kill him, but he defended himself with the Kinniku Curtain, and later blamed some Akuma Chojin to let the past behind and purge the Kinniku Clan from the growing malice.
By Kinnikuman's time, the Kinniku Clan was restored to his glory as a pillar of goodness and friendship, and by Mantaro's time only some comical greed from Ikemen Muscle, Jacqueline Muscle and Harabote Muscle was left in a clan otherwise flawless and good natured.
By the infinite attributions of the Royal Family, they're bound to hold the Kinniku Clan's Chojin Prophecy Book, an ancient book with prophecies reguarding every member of the Kinniku clan and their allies.
--------------------- | | Silverman Goldman | Kinniku Clan Ancestor | ------------ | | Tatsunori Kinniku Sadaharu Kinniku | | Mayumi Kinniku--+--Sayuri Kinniku | --------------------- | | Ataru Kinniku Suguru Kinniku--+--Bibimbap | | Mantaro Kinniku