Hi,
looking for a longplay of said game that I used to play a lot in my youth, but never completely finished.
It is a japanese-themed RPG similar to Ultima in scope but with action-based combat similar to Zelda. 40 Towns to explore, huge main map with 320x512 fields, 24 different weapons and armors, 10 spells to learn, over 500 NPCs, and much more :)
Extensive (German) description is here:
https://www.c64-wiki.de/wiki/Nippon
Web page of the original developers with lots of screenshots and lore (also German) is here:
http://www.nippon-museum.de/