We are a group of backcountry skiers in Honshu for a couple of weeks and went to Tenjin for the day. All of the previous reviews on this website are accurate. The only thing I would add is that you have to make sure that the one ski run that goes to the bottom of the Ropeway is open before you go. When we were there, only the chairlifts at the top were open, meaning guests are supposed to ride up the ropeway, ski inside the tiny ski resort all day and then ride the ropeway back down. Little did we know when we bought our day pass that only got us one ride up the ropeway, and unlimited rides on the two little lifts at the top. So we rode up the ropeway, immediately went and skied the sidecountry back to the bottom of the ropeway and were informed we cannot keep riding the gondola. We gathered from patrol that once the catwalk from the top to the bottom is open, the passes include unlimited ropeway rides and you would have no problem doing sidecountry laps all day for 4000 Yen. You can find out if the catwalk is open before going on their website. If the catwalk is closed you can still do ropeway laps all day, but each additional ride up the ropeway after your first one will cost you another 1200 Yen on top of the day pass. We were able to sneak three ropeway rides out of our one ride pass simply by claiming ignorance, the lack of english speaking liftys at tenjin, and wiping all of the snow off of your skis and gear before trying to get back on the ropeway. Recommend checking this spot out, major big mountain skiing potential just outside the resort.
See our video here