Sa, 25 years of age never had a boyfriend and has never kissed someone her entire life. While riding a bus from work, she meets Bass, a high school student, when they accidentally share a light kiss on the lips. Bass got hooked on the woman who's almost 10 years older than he is and is now determined to win her heart. Things got more complicated when Sa’s first love comes back to her life and tries to win her heart as well. This encourages the high school boy to try even harder to win her heart.