The King was not always called "The King"; it's a divine name he ascended to after unifying Ashihara and establishing the Land of Gods.
Before establishing Ashihara Country, the King was named Okuninushi, also known as the great deity Kuni no Kami.
The Kamiyagawa party is currently exploring the tomb of royal lineage known as the "Country Yielding Group" under Amatsuhiko lineage in this Longevity Palace. The inscriptions on the walls mainly praise the emperors of the Heavenly Grandchild lineage.
Moreover, it's likely that in order to make Amatsuhiko's rule over Ashihara more legitimate, these inscriptions deliberately avoid discussing matters like "Heavenly Grandchild's descent."
So, suddenly coming across a series of frenzied, strongly praising words towards the King, is indeed very peculiar.
As a "former dynasty" emperor, the name of the King shouldn't appear in this Longevity Palace under any circumstances.
