In Japanese mythology, 国産み is the traditional and legendary history of the emergence of the Japanese archipelago, of islands, as narrated in the Kojiki and Nihon Shoki. According to this legend, after the creation of Heaven and Earth, the gods Izanagi and Izanami were given the task of forming a series of islands that would become what is now Japan. In Japanese mythology, these islands make up the known world. The creation of Japan is followed by the creation of the gods (kamiumi).
After the formation, Heaven was above and Earth was still a drifting soft mush. The first five gods named Kotoamatsukami were lone deities without sex and did not reproduce. Then came the Kamiyonanayo, consisting of two lone deities followed by five couples. The elder gods delegated the youngest couple Izanagi and Izanami to carry out their venerable mandate: to reach down from heaven and give solid form to the earth.
This they did with the use of a precious stone-covered spear named Ame-no-nuboko, given to them by the elders. Standing over the Ame-no-ukihashi, they churned the chaotic mass with the spear. When drops of salty water fell from the tip, they formed into the first island, Onogoroshima. In forming this island, both gods came down from heaven, and spontaneously built a central support column called the Ame-no-mihashira which upheld the "hall measuring eight fathoms" that the gods caused to appear afterwards.
Then they initiated conversation inquiring of each other's anatomy, leading to a mutual decision to mate and reproduce:
Izanami accepted the offer and Izanagi proposed that both should circle around the column Ame-no-mihashira in opposite directions, Izanami going right and Izanagi left and on meeting each other would perform sexual intercourse (maguwai). However, when they met on the other side of the pillar, Izanami was the first to speak, saying: "Oh, indeed you are a beautiful and kind youth!", to which Izanagi replied: "Oh, what a most beautiful and kind youth!". Izanagi then rebukes Izanami saying: "It is wrong for the wife to speak first.