That is literally what I saw upon starting a game as Castile. Is this WAD? I'm almost positive the Portuguese haven't discovered Japan yet.
You can also get -200 relations with nearly everyone by messing with the start date.This happens when you play around with the start date before hitting play. If you move the start date to something like 1796 manually, all the nations that exist at that point get their history files loaded. If you don't manually move back to 1444 (ie; you hit the 'Rise of the Ottomans' button), it retains these files..
(Definitely not 100% accurate, but I think I conveyed the main point)