Movie tickets are considerably more expensive, there are far fewer theaters per capita in japan than any other western country, and marketing tactics are weird in Japan in that its been found time and time again the most effective movie campaign to actually get people into theaters is "This movie is extremely popular in the rest of the world", which obviously takes extra time to (a) happen (b) portray correctly in ads (its not just movie is popular, but like "French people found this movie very scary!")
Movies also are a different experience there, with most having booths inside theaters that sell merchandise (like INSANE amounts) and all that requires extra approval time from the studios, manufacturing time, etc since the studio will generally not leak character and plot info to the Japanese distributors just to create extra merch in Japan.
I'm a little surprised at how surprised Bigelow was at Detroit not doing well. In this current time period watching a movie about how bad race relations can be doesn't seem to be a thing most people are gonna want to watch to escape reality. Another surprise though was how critical reception seems to be a bit uneven, I wonder if that hurts its Oscar chances.