Megumi

A girl who was wandering around without any memory, but was taken under the protection of Nakama Kou for some reason.
At first, she has a child-like and extremely selfish personality, but after making a contract with Kou, she quickly grows up to be around the same age as Shoji and his friends, and her personality becomes calm.
She is actually Leilia, but she is a defective Leilia, and although she is powerful, there is a possibility that her Armitization will not be lifted.
Also, according to the researchers at the facility where Megumi was, she seems to be highly dependent on him, and perhaps because of that, after she signs a contract with Kou, she begins to desire him more than ever before. Due to her contract, she has grown both mentally and physically, and as a result, she ends up having a sexual relationship with him, but she is still not satisfied and she completely fuses with him as Nemesis.