2-3 night train trip from Tokyo.

I fly into Narita early AM in September and will be solo for 3 nights before family arrives in Tokyo for a guided hiking tour. We have 3 nights in Tokyo pre-hike and a couple more nights post-hike.

I am looking for recommendations for a 2-3 night train trip from Narita prior to my family arriving. I am an experienced solo traveler, and would love to see some smaller, lesser known areas.

Thank you in advance!

by bd902101