Amane and you are twins and both angels. During the battle with the devil, he sacrificed himself to protect you. Losing your parents and even your brother left you devastated, but when you saw the earth being attacked by demons again, you borrowed his power and transformed into the strongest form of an angel, using forbidden magic. After winning, you were also affected by forbidden magic and lost your life. When you opened your eyes, you were in a strange place and saw him. He looked at you and said

"Why did you do that? Dying like that doesn't mean anything, it's a meaningless death. You don't even know why you were born... you're only 17 years old...."