Spending three hours to film their first kissing scene on Oct. 27 did not result in Lee Min Ho and Park Shin Hye filming the next kissing scene any faster. When they filmed their second kissing scene on Nov. 11, it took another three hours to get it right.

And while it may seem like it would be fun to kiss Lee Min Ho, filming a kissing scene for hours on end is also hard work. Because there is so much to consider, some kdrama kissing scenes can take up to a day.

Taecyeon has said that his "Dream High" kiss scene with Suzy took eight hours to film.

"When I filmed that scene with Suzy, it was my first kiss scene so I worried how I should go about it," said Taecyeon. "We ended up filming that kiss scene for close to eight hours."

It's not just the kiss that has to be convincing but it has to look good from several angles. Even though the Dream High scene was filmed in a Ferris wheel and shot from far away, Taecyeon and Suzy had to keep kissing.

"You can hardly see us," said Taecyeon, "but we still kept kissing anyway."

Actor Joo Won had the same experience when filming kissing scenes in "King of Baking, Kim Takgu." It's not just the cameraman that has to worry about how the kiss looks from different angles.

"It's not just the mouth-to-mouth kissing but the actor must also consider the camera angles," said Joo Won. "It must give the viewers the right type of feeling. I realized it's not easy. Not like the way we'd normally do it."

While a kissing scene may look spontaneous and romantic, the actors have usually discussed it beforehand and even blocked out their moves.

Joo Won has said he discussed his kissing scenes with Choi Kang Hee before they kissed on "Level 7 Civil Servant" asking her what he ought to do. She told him to improvise.

And some stars speak up about what they will or won't do in a kiss scene. Before they filmed the kissing scene at the end of "I Hear Your Voice," Lee Bo Young told Lee Jong Suk that he was not allowed to smoke for hours before he kissed her. She was not sure she could kiss him enthusiastically if he smelled of cigarettes. He agreed and the kiss was heart-meltingly convincing.

It's also hard to feel romantic when there is a whole production crew of people staring at you. But veteran actors such as Lee Min Ho and Park Shin Hye are used to that. Fans of "The Heirs" will agree that the actors created plenty of onscreen chemistry with their kisses in "The Heirs."