YoonA greets her Sugar sister, Sunny, a happy birthday!

It's SNSD YoonA's turn to greet Sunny a happy birthday!

Here's their adorable photo where she expressed, "Happy birthday Sunny unnie♥ sugar sisters"~

Curious about 'Sugar Sisters'? That's because Sunny and YoonA performed Maroon 5's 'Sugar' at their Phantasia concerts.

Happy Birthday Sunny!

YoonA's Instagram