Are English-language ski lessons easy to find in Japan?
Hokkaido is better than Honshu as a rule, but don't make assumptions. It's always good to check, since prices and restrictions on age and mixing ability can be complicated.
Full English-language group lessons, the kind you'd walk into in Europe or North America without a second thought, are genuinely rare in Japan. Where Honshu resorts do offer lessons, the common format is a private group booked at one flat rate regardless of headcount, workable for a family, awkward if you're trying to combine with strangers of mixed ability.
A few places buck the trend properly. Myoko has a snowsports school that's picked up awards for its instruction multiple years running, with English lessons for both kids and adults. Palcall Tsumagoi, a smaller family-oriented ski area, throws in free English-taught lessons for kids over five if you commit to a three-night stay, worth checking if your children are just old enough by the time you'd travel. For a fully organised week rather than day-by-day bookings, Rhythm Japan runs a five-day kids' lesson package that takes the planning out of it entirely.
None of this needs locking in a year out, but it does need locking in before you land. Slots at the well-regarded schools disappear over school holiday windows specifically, so treat lessons as the thing you book right after flights and accommodation, not an afterthought once you're on the ground. If everyone in your party skis at roughly the same level, a private group rate usually beats paying individually for a shared class; if the budget stretches to it, genuine one-on-one time with an instructor still gets people progressing faster than any group format.