Sketchbook is almost necessary during travel. Now, digital camera can make thousands of pictures which you never see again since there are too much of them. But one sketch on location can bring the memory of the whole day so vividly. It is especially exiting to have a travel book in Japan, since many destinations have stamps which can decorate your work.
Stamps from Hakone ropeway and Mejijingu shrine in Tokyo with a quick on location sketch