Tsukiyo Shihōin

"Bahahahahaha! Look at you, Shigekuni Yamamoto! You've stepped off your mantle of as the heartless killer? How boring! Well ain't that good for you. You know what? The moment that mercy boiled in your heart was for that good for nothing soul whom you left. Poor you, sitting in your grave, probably regretting those very few moments of your life that you handed over your entire legacy to a drunkard. Meh, I have other things to worry about than a Sword Demon turned Saint. Goodbye, Genryūsai, was it? Ah yes, Genryūsai, the name that the poor child put onto your head. Well then, goodbye Genryūsai Shigekuni Yamamoto. Enjoy your reincarnations into whatever realm you go to."

- Tsukiyo speaking to a deceased Genryūsai Shigekuni Yamamoto

Tsukiyo Shihōin (四楓院 月夜 Shihōin Tsukiyo) otherwise regarded as Eiki (盈虧 Waxing and Waning Moon) among those in the, is a who wanders across the dimensions for an unnamed purpose. She is as old as the formation of the itself, or perhaps even older than that, considering her casual tone with the likes of deceased. Tsukiyo is one of the ancestors of the currently renown and is heavily regarded as the Grandmaster of, as well as the former tutor to her descendant, and possibly her granddaughter,. Prior to this, Tsukiyo was a of terrifying power; constantly clashing with the likes of the Sword Demons,  and  until she finally submitted to their combined prowess, though perhaps on purpose. It had only been a few years after giving birth to her first child that she once again disappeared from the face of the Gotei, indicating at a fleeting affiliation. Recently, it has also been revealed by Tsukiyo that she is a Yōkai of heritage, indicating at her status as a  (変化 Shapeshifter).