I believe you would like to go to Jigonudani in Nagano.
All information is here. Please check kanto = Tokyo.
From Tokyo station, you take Hokuriku Shinkansen. You stop at Nagano station. From Nagano st.,there are 2 ways with a bus or train.
I found an advantage ticket.
I would like to go there on day so I i appreciate if you give some feed back after your visit :)