I think some people are underestimating the sales for this game in Japan.
Squids are quite popular in Japan in video games, anime (as well as other types of anime *ahem*) and other categories of their pop culture.
Third Person shooters also tend to be more popular in Japan in comparison to 1st person.
My estimate for first week:
US 150k
EU 100k
JP 120k
WW 425k