There are many possibilities to choose from, depending on where exactly in the Kanto area. Assuming you're travelling from Tokyo, some very accessible options include; Karuizawa - 1 hour by Shinkansen from Tokyo, noted attractions include Shiraito Falls, Prince Shopping Arcade, Church Street, Kyu Karuizawa shopping street. There are also onsens located closer to nature.
Kamakura/Enoshima - 1 hour by JR from Tokyo, this ancient city is dotted with shrines and temples as well as home style cafes. The Enoden is also an attraction in itself, loved by locals and tourists alike. Nearby Enoshima has a lighthouse, restaurants, a shrine and caves for interested tourists to explore. There is also the Enoshima Aquarium.