Board Thread:Theories and Speculation/@comment-45444155-20200806114740/@comment-45903789-20200807205213

Izanagi have been used by other Uchihas since before Madara's time. Izanami's purpose was to counter Izanagi.

About it's release classification, I think it is yin release and yang release not yin-yang release, much like a collaboration jutsu.