The capital of Hokkaido, Sapporo is a city of almost two million people but a more relaxed one than its counterparts on Honshu. Easy to explore, it is most famous for beer gardens in the summer and a snow festival (Yuki Matsuri) in the winter. Both of these take place in Odori Park which runs the full length of the main street. To the north of the park the botanical gardens are well worth a visit particularly in the spring when it is in full bloom and for the more active you can hike to the peak of Mount Maruyama for fantastic views of the city.
The city is well known for its food, particular favourites being hairy crabs and chocolate which you can sample at the Ishiya Chocolate Factory. The cherry blossom season arrives later here than on Honshu making May a great time to visit and even if the beer gardens aren't yet open you can join a tour of the Sapporo Beer Museum.