Escalator in Japan is as same as in Europe but there is a difference where you stand.Then, it is not all in Japan.
In Osaka, people stand as same as in Europe, the right side and keep the left side ope for the people who are in hurry. On the other hand, people in Tokyo and other areas stand on the left side and keep the right side open.
I assume that the people in Europe stand on the right hand side due to
1) As same as the highway. Slow cars run on the right lane and the faster cars run on the left lane.
2) Most of the people are right handed, therefore they would like to hold the conveyor belt by his right hand.
However, highway in Japan is different. Slow cars run on the left lane. Therefore faster cars run on the right lane, which means people in Tokyo are obeying as like the highway. On the other hand, people in Osaka rather stand on the right side to secure his or her safety by grabbing the belt.
Anyway, if you are in Japan, except in Osaka, please stand on the left side of the escalator.