The Nyogetsu Ninja (如月忍流 Nyogetsu shinobi-ryū?) were the ninja clan which served the country of Toda in the time of Burning Dawn crisis (and presumably for generations before). Their leader at this time, who turned out to be their last, was Nyogetsu master Lady Kagami.
The Nyogetsu, due to their loyalty to Toda, frequently came into conflict with the Azuma Ninja, the sworn servants of Gohda Matsunoshin, his family, and their country. From the fact that she recognized Izayoi, as well as her reference to "old man Azuma" (Azuma Shiunsai), it would seem that Kagami had fought or encountered Shiunsai some time in her career.
Birth of the Burning DawnEdit
When Toda struck a deal with Gohda Motohide to invade Lord Gohda's country, he took his entire supply of Nyogetsu Ninja with him. Several, including Kagami, Genbu, and Seiryu, went to aid Motohide in the attack on Gohda Castle. Several of these ninja, including Seiryu, were killed by Azuma Ninja Tatsumaru and Ayame. Those who survived fled along with Motohide to Toda's war camp.
At the camp, Tatsumaru battled and mortally wounded Toda. As he lay dying, Kagami approached and decapitated him, took his head to a precipice, and set it on fire. At this prearranged signal, the watching Nyogetsu Ninja slaughtered Toda's samurai army. This event marked the birth of the Burning Dawn.
Whether all the Nyogetsu followed Kagami in the Burning Dawn is unknown, but there are no known examples of Nyogetsu who did not. With the demise of the House of Toda, the Nyogetsu as a clan ceased to exist, and all of its known former members were killed off in the Battle of Gohda Harbor or the conflicts leading up to this.