We've long lamented the lack of a cheap bus option to bring adventurers to Minakami but it seems as if a company have just stepped up to the plate.
Harvest Tours' new Onsen Liner service stops in Minakami on the way up to Yuzawa & Muikamachi.
Departures are from Shinjuku Station, Tokyo Station and Saitama Shintoshin Station. Prices start from 1900JPY per person one way on weekdays and 24ooJPY for peak times (Saturdays from Tokyo or Sunday and holidays from Minakami) and is running until the end of August. Bargain.