Why did Song Joong Ki pop up on the set of That Winter, the Wind Blows? A source spotted the actor while the filming was in progress. The actor came to the set to visit Jo In Sung. The two had previously acted in A Frozen Flower—in fact, they even shot an advertisement together before. Lee Gwang Su also shot a commercial with Song Joong Ki. Sadly, his visit wasn't an indication that he will be joining the cast, but we're still excited for the drama! Are you? You can subscribe for episode alerts here! (Source: www.koreajoongangdaily.joinsmsn.com)