A relationship between master and disciple, an ethical entanglement of love, who can reach the end.
He is an immortal figure, just a legendary person. She is a top killer, and few people in the world have seen her true self. Maybe the encounter was a careful arrangement, or maybe it was a fateful encounter. . . .
When she was 10 years old, she was seriously injured during a mission. At that time, she accidentally entered his forbidden area. Under the twist of fate, he rescued her who was dying. At the same time, in order to survive, she recognized him as her master. "Master, please accept my disciple's worship!" ' After three years of getting along, she never thought that this was just a game, but he had known it was such a game but still fell into it, just because of the child's look and call of master.