Highway buses make five round trips per day between Tokyo's Ikebukuro Station and Karuizawa Station. The one way journey takes three hours and costs 2600 yen.
http://www.japan-guide.com/e/e6031.htmlfrom Ikebukuro area --
0810 at Ikebukuro Station East (Gosaro)
towards - Karuizawa area (1057 eta.) - Nakakaruizawa area (1110 eta.) - Shinano-oiwake area (1116 eta.)
bus(2+2 toilet)
operated by Seibu Kogen Bus, Chikuma Bus
as of 05-May-2014 -- schedule -- prices, maps, offices etc.
0910 at Ikebukuro Station East (Gosaro)
towards - Karuizawa area (1157 eta.) - Nakakaruizawa area (1210 eta.) - Shinano-oiwake area (1216 eta.)
bus(2+2 toilet)
operated by Seibu Kogen Bus, Chikuma Bus
as of 05-May-2014 -- schedule -- prices, maps, offices etc.
1210 at Ikebukuro Station East (Gosaro)
towards - Karuizawa area (1457 eta.)
bus(2+2 toilet)
operated by Seibu Kogen Bus, Chikuma Bus
as of 05-May-2014 -- schedule -- prices, maps, offices etc.
1310 at Ikebukuro Station East (Gosaro)
towards - Karuizawa area (1557 eta.)
bus(2+2 toilet)
operated by Seibu Kogen Bus, Chikuma Bus
as of 05-May-2014 -- schedule -- prices, maps, offices etc.
1850 at Ikebukuro Station East (Gosaro)
towards - Karuizawa area (2137 eta.) - Nakakaruizawa area (2150 eta.) - Shinano-oiwake area (2156 eta.)
bus(2+2 toilet)
operated by Seibu Kogen Bus, Chikuma Bus
as of 05-May-2014 -- schedule -- prices, maps, offices etc.
from Shinagawa area --
0815 at Shinagawa Prince Hotel (East tower)
towards - Karuizawa area (1115 eta.)
bus(2+2)
operated by Seibu Kogen Bus, Keikyu
as of 18-Jul-2014 -- schedule -- prices, maps, offices etc.
http://lazuli.voyage/busList/tokyo/karuizawa