Generally speaking if your only on the ground for 7 days, given storm cycles can be from 2-3 to 4-5 days apart on average, you could really only “hope” for at least one good powder day, anymore is a bonus. Same could apply to Hokkaido with windhold days in lieu of rain days more so experienced on Honshu. It’s always a gamble, it’s weather, we can’t control it nor should we have the arrogance to expect it. Honshus best chances are giving yourself 10-14 days on the ground from 25 Jan - 14 Feb. obviously everyone has different life factors that get in the way and reality is often a bitch but it’s also about expectation management and risk mitigation. Don’t be too put off, we have all had an average or poor Japan experience if you visit enough you will ride the ups an downs.