As an island nation, Japan certainly does not lack for peninsulas - Izu, Boso and of course Noto come to mind - but Sadamisaki is probably the most unusual. Located on Shikoku’s western coast, this long, thin peninsula begins stretching west just south of Matsuyama and doesn’t stop until it’s almost touching Kyushu - you can literally see that island from the tip of the peninsula across a narrow straits. Cyclists probably won’t be spending a lot of time sightseeing here - there’s little to see except green trees and blue sea until you reach the white lighthouse at the end - and so the route can easily be done as a day-trip from Yawatahama. If you get an early enough start, you’ll be able to make things more interesting by taking the main (ridge) road on the way there and returning via the tiny roads on the northern coast. Check the signs carefully and watch the coastline and you shouldn’t get lost - it’s a peninsula, after all. I went in late spring to enjoy the spring greenery; cycling the route in the autumn to check out the leaves is high on my list of things to do.