He could be a different kind of supernatural creature like a yokai-dragon of the Sun? By lore footnotes he looks like a Kostlatyn type, blessing others and not being strong by himself.
Nippon is not going to be ignored by GW and CA, japanese culture is very popular worldwide because anime and manga. I am concerned what yokai could look like a sun... and I think I know the answer: a kitsune emperor shapeshifter with 9 or 12 golden tails. This way they would avoid rivalry with China/Cathay and please the otaku/japanese geeks masses.
In lore its said the emperor of Nippon is weak military, it may be done by doing the emperor a child/teen character, or even turn it into a young empress kitsune shapeshifter, it would make Nippon even viral in popularity outside the usual total war warhammer community. I think they wil do Nippon, and they will do Nippon this way, the most cash grabber way.
I have many more thinkings about Nippon: I concluded thinking Nippon Emperor o Empress will be a human-kitsune shapeshifter because the skaven Eshin learnt magic from the mages of Nippon, and magic of Nippon is very related in warhammer lore to their ninjas.
Also, the only popular yokai wich fits perfectly into Ninjas magic are Kitsunes.
The only supernatural creature with popularity to the level of chinese dragons without being repetitive are kitsunes.
The only possible for an eye-catching Divine Sun emperor is a kitsune with many tails, they may look very supernatural but they are weak, usually known to act with very ninja behavior.
Nippon armies will be peasants, cannons, samurais and ninjas (assasin spellcasters) and top best ninjas will be yokai kitsunes like the emperor, the low tier ninjas will be humans. We may see some other yokais but kitsunes will reign Nippon.
new Undead Legion: Nagash (unlockable for beating game with Undead Legion)The Nameless
Dread King or Walach Harkon
And also give a quest possibility to other mortachs to access/join some Undead Legion recruiting privileges.DLCs for VC BLOODLINES:
Zacharias, Melkhior, Radu the forsaken /Strigoi:
Ushoran, Vorag The Ghoul King, Gashnag The Black Prince, Rametep /Blood Dragon:
Red Duke, Abhorash /Lahmia:z
Nitocris, Ulrika, Naaima