Ignore the review saying it's a dangerous resort for back country. Kiroro has some of the best / most monitored back-country in Japan.

They have opened up the whole backcountry so long as you register in the morning and for the most part it's free of charge. There are certain sections where only paying Mountain Club members (1,500 yen per day or 12,000 yen for the season) are allowed before 11am but the vast majority of slack country is open to everyone from when the lift starts. The whole lot is open after 11. You can always find fresh tracks to be had, and the guys in the place where you register are happy to provide advice about where to go and not to go.

Only drawback is the food. It's overpriced because the only local accommodation is a couple of posh hotels. Bring an Onigiri or just ride the whole day and then head down to Otaru for a proper meal.