I recommend the Clio Sharp So Simple Waterproof Pencil Liner.

I recommend the Clio eyeliner! Since it's a waterproof pencil, it doesn't smudge easily and is great to use during the summer when your skin gets oily. Of course, it's good to use in the fall and winter too! The price is in the 10,000 won range, so it's not too expensive, and it offers truly excellent value for money. I highly recommend it!