The Shimanami Kaido is Japan's only inter-island expressway open to motorcycles — 70km of bridges and causeways linking Honshu to Shikoku across six islands of the Seto Inland Sea. Each bridge is a feat of engineering; each island has its own character. Onomichi is a cinematic hillside port town; Omishima hosts the oldest shrine in Japan devoted to the sea god Oyamazumi. Ride it one-way (ferry back) or as an out-and-back.
Clone it to your planner, customize dates and stops, then ride. All free.