Absolutely loved Shikoku, having made at least 25 trips to the island for work. Having spent more than enough time in the big city and bright lights of Tokyo, Osaka, Kyoto, etc, Shikoku was a nice break. It's much more rural, much less busy, and has a tremendous amount of accessible natural beauty including hills, rivers, etc. It's worth getting a JR railway pass and spending time traveling around this island. Definitely will give you a different take on Japan.