Meoto Iwa, or Married Couple Rocks, are a kind of rock formation seen as religiously significant in Shinto. They are a subtype of Iwakura rock.
According to Shinto, the rocks represent the union of the creator kami, Izanagi and Izanami. The rocks, therefore, celebrate the union in marriage of man and woman.
The most famous pair is the pair at Futami Okitama Shrine in Futami-ura, two rocky stacks off the coast from Ise, Mie, Japan. They are joined by a shimenawa and are considered sacred by worshippers of the shrine. The shimenawa, composed of five separate strands which each weigh 40 kilograms, must be replaced several times a year in a special ceremony.
Wikipedia https://en.wikipedia.org/wiki/Meoto_Iwa
Coordinates 34°30'33.594" N 136°47'17.897" E