I don't find this drama to be very similar to Playful Kiss. The only similarities are the smart cold male and less intelligent playful female (very cliche), the male becomes a doctor, story progresses through school to adult life. Other than that, the scenarios in this drama are completely different. What I liked more about this drama is that the dumbness of the girl and coldness of the boy are toned down and it also had some elements of friendship.
Three different channels on YouTube joined together to sub this show but other drama-watching sites (like dramacool & some others) have been copying their videos. If you want to watch this drama, please watch it on YouTube and support the subbers there! Thank you! The playlist is here: https://www.youtube.com/playlist?list=PLXEhHSH0vJg2QBCLER2c6oV-lIFslgL9K
The playlist is here: https://www.youtube.com/playlist?list=PLXEhHSH0vJg2QBCLER2c6oV-lIFslgL9K