Shin Se-kyung

Yoon So-ah

Boon-yi Lee Re as young Boon-yi Yoon Yoo-sun as old Boon-yi (cameo)

Oh Cho-rim/Choi Eun-seol, the female lead who witnessed the murder of her parents and lived on as the sole witness of the barcode serial murders. She has a strange ability, being able to see smells as patterns in the air. Eun-seol forms a team with Moo-gak, with whom she works to solve barcode murders.

Son Se-dong

Seo Mi-do

Lee Ga-young

So-yi/Dam Kim Hyun-soo as young Dam

(신세경, ) : The series centres around Se-kyung and Shin-ae's involvement with the Lee family. Se-kyung is Shin-ae's highly reserved older sister and finds work as the Lee household's live-in housekeeper after a mad escapade involving her father's debt to some loan sharks. She is diligent and frugal, but also initially lacks aspirations. She is clearly more intelligent than her position allows for and longs to go to school as her peers do. Other characters come to admire her, particularly Jun-hyeok and Julien. She is unaware of most of her virtues (including beauty) and approaches the modernity of Seoul with wide-eyed bewilderment and willingness to try new things. She knows Jun-hyeok's love for her before he reveals it. She does like Jun-hyeok, but she really loves Ji-hoon. Julien also had a crush on her from the beginning, which is revealed later in the series. She eventually quits her job to immigrate to Tahiti with her family, but it was hinted in the last episode that she faced a tragic death along with Ji-hoon who was driving her to Seoul - Incheon International Airport in a car accident as their car slipped due to heavy rainfall.

Young Cheonmyeong

Young Seo-hee