Booked a superior trple twin room (for 2 adults and 2 kids 13 & 11), and the check in staff kept trying to give us a room with 3 single beds. It required intervention from the hotel manager to finally get the type of room we had actually booked. When we got to the room only had 3 sets of towels, Yukata, and toiletries.
Breakfast was 12,000 JPY for 4 people and was not worth the money. I've had the same budget buffet breakfast in the business hotels for less than a 1/3 of the price.
The hotel is in the middle of nowhere, so you need to bring a lot of snacks, drinks, etc, or travel several kms to the nearest convenience store or further for shops.
On the plus side, the hotel looks very new and is very clean. The kids activities are great, but a tad pricey.