Stayed overnight.
Important points are:
Room: old and dated. Evidently our room was a smoking room and everything including linen smelt of cigarette smoke. No hair dryer in the room; you are expected to go up to the main bath.
Meal: our dinner buffet was noisy, crowded, with average to ok food. One male manager in particular was shockingly rude as he bluntly attempted to correct my cutlery use (“NO! THIS IS THE BOWL FOR SUSHI, NOT THIS”). Frankly the staff here (and the hotel in general) appeared rushed and lacking the usual Japanese omotenashi.
One interesting point was that there did not appear to be a Japanese patron in the massive buffet dining area, despite there being plenty in other communal areas of the hotel. Given that the website states there being two buffet restaurant places, I have a suspicion that they segregate Japanese and non-Japanese customers into different dining halls.
Bath: the quality of onsen water is excellent, but bathing facilities so-so. Private bath costs an eye watering 3,200 yen for 50 minutes (establishments in other area charge as little as 1,000 yen for similar usage).
Location: this hotel is further away from Noboribetsu onsen town than any other, and includes a 10 minute uphill walk that can be perilous in winter. There are definitely better located places in town.
Overall, not at all a good value for money and an unpleasant experience. I will avoid this place in future specifically. There would be better places in this town for sure.