The Yin Replication Technique, (陰の複製, "In no Fukusei") also fittingly called the Shadow Replica is a truly peculiar Genjutsu developed by the very same cultists that developed the base of Isamu's other peculiar technique, She Who Invites; it was found together with the former and albeit it was incomplete at the time - Isamu later managed to complete it by making use of his great skill in Genjutsu coupled with his unique gifts and unusually keen mind. As it name implies, it can only replicate that which isn't actually real, and it cannot be used to replicate anything but Genjutsu.