I want to ski at Shiga kogen on 5-6 December 2018 does the learner slope (beginner slope) open on that period.
Some of Shiga Kogen’s courses should be open on December 5-6. Most likely, most of the Kuma-no-Yu ski resort should be open around then. It has several beginner and intermediate runs that should be open. You can see up-to-date information about open courses on Shiga Kogen’s ski resort site here (see Kumanoyu’s lift status here).
You may want to contact Sugiyama Ski School and see if they will have English-speaking instructors available by early December.
I hope that helps!