Her Name

Noonim means older sister

I think Noonim is a shortened version of Noona-nim meaning older sister with a high status or an older sister that you respected so much.

Noonim means older sister, same as the word 'noona'..

Their only difference is that noonim is formal and noona is informal.

I just decided to follow through from chapter 1 when they used the original korean honorific instead of using 'sister' in translations :)

Hiii (●'◡'●)ﾉ , uhm Ran is really her name. Noonim means elder sister in formal korean(there’s still lots of branches to this, but this is mainly what it is). So it’s a sign of respect or address to her. So, people who may be older than her or not related to her may address her in a different way, like her name or her position title and such.