The Tobishima Kaido is a ~30km cycling route just West of the Shimanami Kaido. Like its more popular sister route, it spans 7 islands of the Setouchi (Seto Inland Sea) and crosses 6 bridges. It is accessible by bike via the bridge from Kawajiri on the West and also several ferry points on the Eastern side.
This route is much less traveled and does not have all of the amenities like the Shimanami Kaido, but it is much shorter with a flat coastal route with beautiful views. You will not find convenience stores every few miles, but there are some as well as various restaurants and cafes. The ride has a much more village feel than the Shimanami Kaido and the locals did not seem as careful about cyclists on the road.
One of the highlights of the route is the Toshimao Bridge (pictured above) which sits incredibly high for what I can only guess is for large cruise ships or cargo ships to pass. It is a thrill to ride a bicycle over! The islands have some museums, hotels/campgrounds and points of interests to stop at along the way. For cyclists it is another beautiful route on the Setouchi connecting the main islands of Honshu and Shikoku.
Map credit and more details on the route from Cyclonoie Guest House in Imabari