Her parents died, so she went up the mountain alone to become a disciple. He was young and accomplished, and his sword skills swept the world. The two are similar in age and are both teachers and friends. He taught her carefully, hoping to resolve her three lifetime sins. He was a monster in one life, a demon in two lives, and a sin in the fourth life. One misstep can lead to eternal life and eternal damnation. To love or not to love is the most difficult choice.