Shikoku is by far the most remote and least traveled of all regions within Japan. As the region doesn't have access to the bullet-train, it is often overlooked.
Nevertheless, the region has some of the best natural wonders in all of Japan. Make a pilgrimage to the Buddhist temples, or attend one of several festivals. Take time to sample the local udon, or the many citrus fruits grown in the region.
The most convenient airport in the region is Matsuyama Airport.