On January 11, 2012 Yoon Gun tweeted, “A Yoonseo duet picture with Seohyun” and posted a selca picture taken with Seohyun. The day before on January 10, he posted a picture of Seohyun recording. It was accompanied with the tweet, “This is the owner of a very clear and beautiful voice.”

Their duet song “Don’t Say No” will be released on February 13 at midnight. (Korean Time) Seohyun had also given a brief 20 second teaser of the song through the mobile messenger program “Kakao Talk.”

Netizens that came across the picture of the two together stated, “The two look like lovers,” “They look so friendly together that I am anticipating the duet song,” and “The two are so good-looking.”