Thanks yllwsmrf and uji for your help.
I will be traveling along, and as for my budget in kusatsu for hotel, it could be anything upto 18000 yen a night jus for the hotel, but I'd rather spend more money on other things rather than the hotel.
http://www.iijimakan.com/i like the idea of iijimakan offering 8 course dinner and breakfast for 6500yen, and the place is rather close to the Yubatake, but it's quite difficult to book there, Kusatsu Onsen Inn Owners Cooperative
can help me book, but they charge 1000yen on top.
http://www.gokurakukan.com/Gokuraku-kan is good, at about 8500 yen without meal, the place looks good, but hard to reserve a room.
http://www.ohruri.com/hotel_12/is really cheap, and I can book through www.booking.com at 13000 yen for 2 nights including breakfast only.
I do prefer to go there and book a hotel or ryokan, but uji recommend me not to, as it waste time, and i'll have a big problem if no room are available.
Is it recommended to as my hotel in ueno when I get there on the 6th, to do the booking for me or will this be too late.
all in all i'm still deciding which of the 3 ryokan to choose, theere is more chance i'll go for the iijimaka.
I will be spending most of my time out of the hotel, even if i paid for dinner or breakfast, i'll probably be eating outside.