18 Year Old Muscle Queen Seong-hye's Sex Scandal.

Ji-min is married to Hyeon-soo, a married man with a child. However, Woo-yeong wasn't Hyeon-soo's own son either. The age difference is so small that she feels uncomfortable in her relationship with Woo-yeong. On the other hand, Woo-yeong falls into a sense of self-doubt that she feels love from Ji-min and that feeling from her mother, but accidentally finds out that she is an adopted child and confesses her heart to Ji-min.