Japan’s most famous Wedded Rocks, bonded by a sacred rope, are off the quiet Futamigaura Coast. The bigger rock is the husband, and smaller rock the wife. (Gender equality wasn’t prevalent yet in the old days.) The bigger rock has a small torii on the peak (upper right photo).
A photo of the Wedded Rocks with no people in it can make it hard to discern how big the rocks are. At first, I thought the small torii might be the height of the average man. But it’s only waist high. The rocks were much smaller than I had imagined.
The sacred rope (consisting of five strands) is replaced three times a year (May 5, Sept. 5, and Dec.) with some fanfare. The old rope is cut up into small pieces with sickles. The new rope is then strung across the two rocks (lower right photo). With the rope across, the Wedded Rocks also function as a torii gate to worship a large sacred rock in the ocean beyond and the Sun Goddess. In summer, the sun rises between the Wedded Rocks. And in winter, the moon rises between the rocks. This attracts a lot of photographers.
The Wedded Rocks belong to nearby Futami Okitama Shrine (二見興玉神社) right on shore. The shrine is dedicated to Sarutahiko and Ukano-mitama, deities for pathfinding and land/sea transportation safety. Since they are closely associated with travel, frogs are the deities’ messengers and symbol (left photo).
In Japan, frogs are associated with “returning home safely” or “getting money back.” Because “frog” pronounced in Japanese is “kaeru” which is also a homophone for the word meaning “to return” or “return home.” Therefore, it’s a lucky charm for travelers and money lenders. In the old days when traveling was a hazardous undertaking, pilgrims who traveled to worship at nearby Ise Grand Shrines prayed here for a safe return home.
Frog statues are also common household and outdoor garden ornaments in Japan. I do have a small frog next to my front door to wish me a safe return whenever I go out. It has worked well so far. 
The Wedded Rocks in Futami are a short walk from JR Futaminoura Station on JR Sangu Line that starts from Toba.
Official: https://futamiokitamajinja.or.jp/
English: https://www.iseshima-kanko.jp/en/see-and-do/1292