Yoona and Taeyeon's selfie

Taeyeon andYoonatook a photo together.

Taeyeon posted a picture on her Instagram saying, "A day without you is stress for me".

Yoonais standing close to Taeyeon and is making a cute pose with her eyes closed. Taeyeon is scratching her head as if she's shy.

Tae-yeon said, "My sister came for me on my fifth special day".

Meanwhile, Tae-yeon is currently promoting her first solo album "I". Her realistic life can also be seen on the cable TV OnStyle.