Japan is a Train-based Society. Public transportation in Japan is highly developed in metropolitan areas and at sightseeing destinations. A large percentage of people travel by train, so it is common for major stations and trains to be crowded throughout the day.
You can take your bike on any train in Japan but it must be packed with a bike bag. Remember that you don't pay extra for taking a bike on the train, even on the Shinkansen super-express train.
If you know your name's hotel, you can send your bike directly there from the arriving airport, using private transport service as Yamato Takkyubin or Sagawa Takkyubin. >>Click here to know more<<
ARRIVING IN KUSATSU BY TRAIN AND BUS FROM TOKYO
1. VIA NAGANOHARA-KUSATSUGUCHI STATION
There are various ways to get from Tokyo to Naganohara-Kusatsuguchi Station, the nearest station to Kusatsu-onsen.
The most convenient is by direct limited express train from Tokyo's Ueno Station, requiring 2.5 hours and costing about 5000 yen for the one way trip. However, there are only around three round trips per day.
Alternatively, you can do the whole trip by local trains, which takes about four hours, requires a transfer of trains at Takasaki station and cost 3020 yen one way. Faster and more expensive is taking the Shinkansen super-express to Takasaki and transfer there to a local train to Naganohara-Kusatsuguchi Station.
From Naganohara-Kusatsuguchi Station there are JR buses to Kusatsu Onsen (30 minutes).
The train journey is covered by the Japan Rail Pass, JR Tokyo Wide Pass, JR East Nagano Niigata Area Pass, JR East Tohoku Area Pass and JR East South Hokkaido Pass, but the bus ride is covered only by the Japan Rail Pass.
2. VIA KARUIZAWA
Take the Hokuriku Shinkansen super express from Tokyo to Karuizawa (70 minutes, around 5500 yen) and then a bus (Seibu Kogen Bus or Kusakaru Kotsu) from Karuizawa to Kusatsu Onsen (80-100 minutes, 2200-3880 yen). JR passes are not valid on the buses between Karuizawa and Kusatsu.
3. BY BUS
There are multiple direct JR highway buses from Tokyo (Shinjuku JR Highway Bus Terminal) to Kusatsu per day. The one way trip costs 3300 yen and takes about four hours. JR passes are not valid on these buses.
Highway bus services usually have a cargo source beneath the passenger compartment which its plenty big enough. If you know which bus company you'll be using you can ask ahead of time. In the worst case, you can bag them and have them sent by an express service.