the 20 kings didn’t exist
Imu "imagined" them, the whole story was a big lie
Imu was the only king and Lily was his lover
Lily betrayed him and got killed
Imu created 5 beings through his imagination = the 5 elders
They’re based on his enemies, you could say that they’re evil counterparts of them
Blonde Gorosei (Mercury) = Sora
Ghandi (Mars) = Musashi Shimotsuki
Saturn = Nika's father, the king of the ancient kingdom
The tall elder (Jupiter) = Wodan the giant
The bald elder with the giant moustache (Venus) = the first Pirate/explorer Leif, also known as the king of the golden kingdom (he’s Roger's ancestor)