Halo has never been a hot hit in Japan, and Halo 4 hasn't changed that in the slightest.
Halo 4 launched two days ago in the land of the rising sun, and judging by some photos posted by Akiba Blog it isn't faring so well. Unlike its older brethren, marketing or availability can't be cited as the cause as you'll see in the visual evidence below.
In this image you can see a ton of Halo 4 copies next to a sign that says the store is sold out of Animal Crossing: New Leaf, a game that launched on the same day. I guess animals are more important than saving the world from the Covenant.
And this is a bunch of Halo 4 marketing jazz sponsored by yours truly, Microsoft. As you may of notice there's a line of exactly 0 people standing in front of it.
The official Japanese software charts for the week should be out in short order, but don't expect to see Halo 4 anywhere on there.