According to "Kojiki," Tsukuyomi was born from the right eye of Izanagi as she purified herself when running back home from Yomi (the world after death), as well as Amaterasu from her left eye and Susanoo from her nose, and together they comprise Mihashira no uzuno miko (the three noble children).
『古事記』ではイザナギが黄泉から逃げ帰って禊ぎをした時に右目から生まれたとされ、もう片方の目から生まれたアマテラス、鼻から生まれたスサノオと共に三貴子を成す。