Ame-no-kagaseo

An enormous figure would appear behind Yomi, if push came to shove, of course due to the lage consumption of chakra. A fully coated, pitch black figure with a golden crown, followed by a skeletal set of wings; and finally a giant serpent that would trail behind said figure. Being the feared embodiment of Lucifer, of Japanese folklore, each feature would represent it’s background history. From the appearance of death itself, and a snake from behind that would assist in battle. In battle, the wings would be for the defense of Yomi Uchiha, and the weapon would be an incredibly large katana with a chain that would reach to it’s other hand. It's full abilities are unknown due to the vast amount of chakra needed for use.