Here is an interesting development: Prince Snow Resorts is making it free for kids up through 6th grade to ski at (most of) their ski areas. Also offering free lessons, rentals, and other things for kids at their resorts -- details of what exactly is free vary by resort.
This means kids ski free at Furano, Shizukuishi, Naeba, Kagura, Muikamachi Hakkaisan, Manza Onsen, Karuizawa Prince Hotel, Myoko Suginohara, and Sayama. Yakebitaiyama will be free only on specified days (but which ones seem not specified yet).
Makes it tempting to even try to brave the evil Kan-Etsu and hit Naeba/Ka