The water come from Mt. Hoousan which is one of the top mountains in Minami Alps. It will be so beautiful in May because all snow of the mountain melt and the amount of water get much higher. Also, May has great green leaves. Koyo, Autumn tints, are also beautiful in Fall.
Shoji Fall and the road will be closed in winter (from 12 to 4) Also, it will be closed after the heavy rain.
Access to the Observation easy, but to reach the bottom of the fall required high mountain climbing skill. So, DO NOT try to reach the bottom unless you are with some who knows how to get there. It is very DANGEROUS.