The week before Christmas. International tourists haven't arrived. You can stay slope-side for half price. However, lower elevations (like Rusutsu’s base) may be grassy. Stick to high-alpine resorts like Shiga Kogen or the top lifts of Niseko Annupuri.
The terrain. Resorts like Happo-One (Hakuba) open their highest peaks (Usagidaira). You can ski 1,000-meter vertical runs in a t-shirt. The backcountry becomes accessible without avalanche risk from new snow (though wet slides are a risk).
Since you can't predict that six months out, book for . Statistically, it offers the deepest base, the lowest chance of rain (rain happens in Honshu in Dec/Jan), and the highest chance of at least one bluebird day.
