Bus between Kusatsu Onsen and Manza Onsen

Due to some reason (unclear for me as I do not read Japanese) Seibu Kogen Bus has suspended their service between Kusatsu and Manza: http://www.seibubus.co.jp/kogen/jikoku/2015natsu_onsen.pdf and http://www.seibubus.co.jp/kogen/jikoku/2015natsu_eki.pdf .

Is there any other oppurtunity to reach Manza from Kusatsu by bus?

And what is the reason of service suspension? May be some suggestions how long it will last?..

Thanks!

Suspension of service is due to increased volcanic activity at Mount Shirane:
http://www.japan-guide.com/e/e7406.html

It has been a while since the volcano's alert level was raised, and nothing has happened ever since. It seems that the volcano does not currently shows too many signs of immediate eruption, but it does not seem to have fully calmed down, either. It is difficult to predict how long it takes until the situation normalizes and bus service is resumed. I would not assume the situation to normalize too soon.

By car/tax, it is possible to travel from Kusatsu to Manza via Shirane, but by public transportation you have to make a big detour via Naganohara-Kusatsuguchi and Manza Kazawaguchi. See the map here:
http://www.japan-guide.com/e/e7495.html

Thanks a lot, Uji-san! You are very helpful as always. :)

What about the reason of bus service suspension. Google Translate says something about traffic jam due to a partial destruction of the road.

Actually, you are right! The reason is not the volcanic activity. The reason is a damage to the road because of which large vehicles like buses are not able to pass. I am not sure when the problem will be resolved.

Yes, I see...

How do you think, how much could be a taxi ride from Kusatsu to Manza?

Probbaly around 8000 yen one way.