250k-300k would be a good baseline for FF If for the FW in Japan. 500k seems too high for a Fire Emblem game for a first week.

Does anything sell that much in Japan beyond Dragon Quest and Pokemon?

Retail looks around 250k considering Boutros weekle report post.
Maybe 100k for digital.

Dont forget this is Both Shipped+Digital. We know The game shipment exceeds Awakening (FE:A had 300k Shipped with 256k Sold). 

FE:IF is 70% sell through day 1 and sell outs  during the week. RETAIL= 300K+

Soooo It sold 340k Physically, from Media Create. Not sure if the digital sales would be around 160k (surprises are always welcome), but its still a pretty good achievement, especially comparing to Awakening.

EDIT: And next week or in 2 weeks, it will most likely Outsold Awakening! 

Where did you get the 340k figure? I only saw 260k + 42k for special edition.

I doubled the special edition since it has 2 copies. Or that doesnt work? 

Dunno.