Day 1 – From Okayama, take a train over Seto Ohashi Bridge on one-hour ride to Takamatsu, where you'll spend the night. Visit Ritsurin Park, a beautiful garden, and then head to Shikoku Mura Village, an open-air Edo-Period museum.
Day 2 – Take the train one hour west to Kotohira, where you can visit Kotohiragu Shrine and the nearby Kompira Grand Playhouse, one of Japan's oldest Kabuki theaters. Head onward to Matsuyama, where you should spend a couple relaxing hours at the delightful Dogo Onsen Honkan bathhouse before retiring to your hotel.
Day 3 – Tour Matsuyama Castle, one of Japan's few original castles, and then take a 20-minute train to the picturesque village of Uchiko, which boasts some fine old homes and buildings dating from the Edo Period.
Day 4 – For an up-close and personal tour of the Seto Inland Sea, head to the nearby Shimanami Kaido route with its dedicated hiking and biking trail (rental bikes are available) connecting six islands and extending 69 kilometers (43 miles) all the way to Hiroshima Prefecture. Stop off at the Shiyoden Treasure Museum to view its astounding collection of samurai armor and swords.