He's making a special appearance because of his loyalty to the drama's writers, the Hong Sisters. They had previously written the script to 'The Sun of My Master', which So Ji Sub starred in back in 2013.

He filmed for the episode back on May 7, and his cameo character, a cafe owner on Jeju Island, is said to say a particular catchphrase that his previous drama character often said to bring some amusement for drama viewers!

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The drama airs its first episode later today, starring Kang So Ra and Yoo Yun Suk, so be sure to watch it!