It advertises itself as just 2.5 hours from Tokyo so it is certainly possible to do a one day trip from Tokyo.
It was formerly known as Koumi Re-Ex Ski Valley but changed its name in Sept 2022 to Chateraise Ski Valley Koumi.
You can check out their website in the link provided, however, as of the last time this page was updated, there was no English or second language mentioned. The same operator, operates Charteraise Ski Valley Nobeyama (previously known as Chateraise Ski Resort Yatsugatake).
New winter sports are permitted on chairlifts 2 and 5 (courses E, F and L). Any devices you use must have a breaking harness.
Period of Operation
From Dec 9, 2023 to Mar 31, 2024 (estiamted)
While the ski school only seems to be offered in Japanese, the diversity of the schools is tremendous. You can choose from a regular ski school sponsored by the Ski Association of Japan (SAJ), a snowboard school sponsored by the Japan Snowboarding Association (JSBA) or freestyle school.. Freestyle school offers lessons on moguls, jumping etc.