Stare at a dense Japanese map in a subway for a while and you may start to think everything is upside down.
You may be right. While I have seen this occasionally in some other Asian countries, Japan regularly orientates north in whichever way the mapmaker wanted. Usually it seems to be aligned with the direction a viewer of the map is facing.
In Japan always look for the direction of the N or 北. In this example from the Osaka subway, north is pointing down, as indicated in the upper right.