Among the most suggested day trip from Tokyo, Kamakura is the option that I usually recommend, both because it is the easier to visit from Tokyo, but also because it is full of interesting things to see and with a very relaxed and many from other places in Japan.

Kamakura is most famous for the Great Buddha of Kamakura, but this is certainly not the only reason to visit it! This pretty town is a coastal area, full of hiking trails in the mountains, many Buddhist temples and full of beautiful gardens and nature.