Like for Likes- Korean movie, Yoo Ah In is involved in a noona romance here. Plus, it has Kang Ha Neul as well.
My Only Love Song- Historical romantic comedy, she's a noona but it's only like two or three years so it's not noticeable. They do mention it in the drama (She's younger in real life).
Eternal Love aka Ten Miles of Peach Blossoms-She's 90+ thousands years older xD
I Can Hear Your Voice is a NR but the lead is still in HS for the first part of the drama, there's a second couple in a NR in Another Miss Oh, but not the leads.
I have realized that I haven't watched many noona romances.