Depends on how it's being written. If it's written horizontally, Japanese is read left to right, like this:
1 2 3 4
5 6 7 8
If it's written vertically, it's read top-to-bottom, right-to-left. Like this:
5 1
6 2
7 3
8 4
The latter way is generally how books are printed, which is why the front and back are reversed from what we're used to in English.