Lots of English brochures and maps (for Niseko and beyond), 200m down the street outside JR Kutchan Station. There's a smaller information centre (open 9am to 6pm) in the train station.
Near the Hirafu gondola (and where direct buses to/from New Chitose Airport originate and terminate), with English-language information. Open only during the snow season.
At JR Niseko Station, with pamphlets, maps, bus timetables; can help with bookings. It also has a centre at the View Plaza Michi-no-Eki on Rte 66 heading into town.
English hiking maps and information on the latest weather and trail conditions. Just above Goshiki Onsen, at the start of the hiking trail.