Keys of Norn (ノルンのカギ), Messiah's Horns (メシアのツノ), and Messiah's Eyes (メシアのヒトミ) are important items found in Devil Children Black Book & Red Book.
In ancient times Lucifer and Michael made a sacred pact to one day initiate Ragnarok or Armageddon when the promised time comes. The Goddess Norn oversaw the pact and created seven keys, which she then split into fourteen pieces, seven eyes and seven horns, which were given to the demons of Expanse. The Angels were tasked with watching over the sacred room where Hoshigami sleeps. Lucifer gave the Rainbow Eye and the Rainbow Horn to two of his wives, who passed it on to their children Setsuna Kai and Mirai Kaname. The eyes and horns allow humans to travel through the Expanse, which Zebul displays by using it to send the two Devil Child's to Center Land.
As the two use the objects they receive glimpses of their father, who attempts to speak to them. As they retrieve more of the horns and eyes his words become clearer. Each object sends them to the land whose color corresponds with it, with the Rainbow Eyes/Horns sending them to Center Land. In the Dark Palace after Azel's defeat the seven belonging to the devil child who is not the protagonist will be hand over to the playable devil child, and the 14 objects will merge to take their original form.
In the organ room they will be used in the organ of the three Goddesses of Fate, which will either awaken Hoshigami or initiate Armageddon.
- Rainbow Eye/Horn - Mementos of the two devil children's mothers. It is taken by Azel and given to Tyrant Mammon, who returns it to them in Fire Land.
- Blue Eye - Given to Mirai Kaname by Azel. Used by him to send her to Ice Land.
- Blue Horn - Given to Setsuna Kai by Diana.
- Gold Eye/Horn - Obtained from Tyrant Hel in Ice Land.
- White Eye/Horn - Obtained in Marble Land by winning the Ballroom Competition.
- Green Eye/Horn - Obtained from Tyrant Isis in Sand Land.
- Red Eye/Horn - Obtained from Tyrant Belial by beating him in Forest Land.