Before the beginning of time, Amaterasu and Tsukuyomi were happily married and spent their days together as both the sun and moon were out constantly.
Rising Action
But then, while Tsukuyomi was inside of his house, he found a body. His brother's body. Tsukuyomi was shocked and went around asking everyone who had killed his brother, but everyone said they didn't know. He got to his wife, the only person he hadn't asked.
Climax
He yelled at his wife but she did not understand why. They both got into a screaming match, neither of them trying to understand the other.
Resolution
As a result, the sun and moon from the view of the Earth was shaking and moving erratically. People began to notice what was going on outside of the Earth, and one of those was the god of wisdom, Omoikane.
So, Omoikane flew up to the moon and found the couple arguing. He proposed a solution, where he could be the judge of a court case and he'd decide who was innocent or guilty.
Omoikane held a court case, and he determined that both sides were innocent. He suggested a compromise, and so the goddess of the sun and the god of the moon split up, and so Amaterasu moved out and lived away from the moon. The sun and the moon were no longer constantly up, and instead there were transitional periods, called the sunset and the sunrise.