Morgana is a mysterious being with ties to Mementos, the incarnation of the Collective Unconscious. He doesn't know who he is, and seeks answers to restore his memories.
While investigating Palaces, he encounters Ren Amamiya and sticks with him since. During the group's activities as Phantom Thieves, Morgana acts as their second-in-command and guide.
To his teammates, his code name is Mona.