Travel to Kusatsu Onsen

Dear all,

I will visit Kusatsu Onsen in late March 2024. My plan is to take Hokuriku Shinkansen from Tokyo to Karuizawa and take a bus there to Kusatsu Onsen.

Is the bus ticket is easy to buy at ticket counter or I should reserve in advance?. I think the bus is operated by Seibu Bus or Kusakaru Kotsu. Am I correct ?

Thank you for every answer.

Is the bus ticket is easy to buy at ticket counter or I should reserve in advance?

You pay on board of the bus when exiting. Reservations are not possible. It is explained here:
https://www.kkkg.co.jp/bus/timetable/en-timetable.pdf

I think the bus is operated by Seibu Bus or Kusakaru Kotsu. Am I correct ?

Kusakaru operates multiple buses per day. Seibu just one bus per day and only on weekends.