Another reviewer was probably at Asahidake with his skis in June!
This place is the BEST powder mountain I have ridden. It's all about the BC - plenty of variety in terrain and sensational steep tree runs and shoots. Make sure you have your full BC gear as it's a relatively short 20-30 min hike out to some supurb powder lines.....
Asahidake has some of the best powder snow in the world, and plenty of it. Terrain is relatively good too. The down side is that all this snow means that the weather is often bad. Hitting a wind-free, cloud-free powder day is like winning the lottery. If you really want to ride "The Day", expect to be at Asahidake for at least 7 days, and have 6 bad ones. It is not a resort, so don't expect it to be one. It's the back country with a single ropeway access. The area at Asahidake is not patrolled. There is no immediate rescue on hand. Understand what this means, and treat the back country with respect.
Asahidaki has only 1 lift. The nearest airport is Asahikawa. The snow is awesome. The terrain is awesome. The onsens at the hotels at the base of the hill are awesome. I love the place.