An organization of Iga ninja formed by a disgruntled shinobi calling himself Vengeance who believed that Fujibayashi Nagato, the last of the jonin not away on assignment, was unfit to administrate the ninja clans by herself. Enough ninja joined his cause to make the Igamono a serious threat, one which most clans shied away from, choosing to remain neutral in the conflict between revolutionaries and those who supported the status quo.
They were eventually defeated in a single night when Fujibayashi allied herself with the Hashinara clan and spread rumors that they would be meeting in a certain teahouse in Iga. When the leaders of the Igamono ambushed them there, they were all killed by the Hashinara, Fujibayashi, and her retainer Tsukuda Katsuo, save for Vengeance, who was taken prisoner and remains in Wakigami’s dungeons.
It is said that the leaders of the Igamono wore extreme disguises and called themselves by strange, single-word foreign names in order to distance themselves from other ninja, so that they may better represent their cause.