Seohyun knew she had to write a song when she heard the melody of the music. It is just the kind of melody that she like. Soft yet have a nice beat to it. Words started forming in her head. She quickly takes out her notepad and pen and started writing down the words forming in her head. When she finish writing the first verse, she smiles triumphantly to herself. She re-reads whatever she has written and an idea form in her head. She wants to dedicate the song to none other than her two unnies who has went through thick and thin with her. Seohyun had always knew Taeyeon and Tiffany have a special bond. But both Taeyeon and Tiffany has never been able to cross the thin line of being just friends. The stake is too high. What if the other don't feel the same way? And this is where Seohyun step in and devise a plan to help her unnies convey their feelings for each other. With a song. Once and for all.