Some of the most successful dramas have been based on mangas. "Boys Over Flowers," starring Lee Min Ho and Kim Hyun Joong is probably the best example as it got good ratings and achieved international fame. The drama about four spoiled rich boys who rule a school is based on the manga "Hana Yori Dango." "City Hunter," which also starred Lee Min Ho, was based on the Japanese manga by Tsukasa Hojo and had Nielsen ratings of almost 20 percent nationwide.

But a popular manga storyline is no guarantee that a k-drama will succeed even if that manga has previously been successfully adapted in other countries.

The currently running manga-drama "Tomorrow Cantabile" was a major hit in Japan, where it was called "Nodame Cantabile." It stars top actors Joo Won and the critically praised Shim Eun Kyung. But so far the ratings are not stellar. It premiered with a decent 8.5 percent in the ratings but by the second episode it was 7.4 percent and by the third episode it had dropped to 5.8 percent.

"Pretty Man" was another example of a manga-based drama that did not do well. The drama starring Jang Geun Suk playing the prettiest man in the world, and IU as the woman who adores him, was a highly anticipated adaptation that never got top ratings.

Manga-based dramas that did well include "To The Beautiful You," based on the Japanese manga "Hana Kimi," "Goong," which was based on a Korean manhwa and "Playful Kiss" based on the manga "Itzahura na Kiss."

This month three new manga-based dramas began. While "Tomorrow Cantabile" is getting a lukewarm response, the other two show promise. "The Liar Game, starring Lee Sang Yoon, Kim So Eun and Shin Sung Rok, is based on the manga series "Liar Game" by Shinobu Kaitani. In this manga-drama, contestants participate in a game show where they can win $10 million dollars. The only catch is that they have to lie and cheat to get the money. And the contest hosts have chosen basically honest decent people, such as Kim So Eun's character, to play. Since it is being shown on a cable channel, you can't really compare the ratings to regular network show but the second episode's 1.05 rating is a respectable cable rating.

And then there is "Misaeng." This drama about a hellish workplace is adapted from the manhwa by "Misaeng" by Yoon Tae Ho. It's the story of a baduk player who has no office skills but winds up in an office where he is bullied and looked down upon by the other interns. This drama is also on a cable station and earned ratings of 2.35 percent by its second episode.