Na-Young is revealed to wear Sherlock Holmes panties when Han-Gyul trips and pulls down her shorts. Although she blushes, she see,s to recognized the mistake and not chastise him for being a pervert.
In spite of this delay, she has appeared from the start and has a short haircut. Similar to Yang Miri but without the antennae in the center.
In chapter 33 she has a chest measured 85.3cm.
This makes he friend with the black hair tied to the side of her head jealous (who only got 83.2cm) and accuses her of stuffing her bra.