The Scholar Who Walks The Night is a 2015 Kdrama based on the Manhwa of the same name. The series is also known as Vampire Of The East (Korean - Bameur Geonneun Seonbi).
Some spoilers for both the drama and the Manhwa.
Jo Yang Seon (Lee Yu Bi) is a cheery bookseller who disguises herself as a boy to make ends meet for her family. She meets an enigmatic yet handsome Scholar named Kim Sungyeol (Lee Joon Gi/Lee Junki) who has requested she seek a memorandum by the Crown Prince Junghyun. Little does she realise that Sungyeol is a vampire who once served the Crown Prince Junghyun 120 years ago and has his own reason for finding this book as it contains a secret to killing a vampire named Gwi (Lee Soo Hyuk). Sungyeol is the current Guardian Vampire who searches for other vampires who break any rules. He took over as the Guardian after being bitten by Gwi's former mentor Hae So who gifted him his strength and abilities and also advised him not to remove a black robe which allows him to walk in the sunlight.
Normally keeping to himself and not expressing much of his feelings, Sungyeol grows closer to Yang Seon after rescuing her a few times from danger (even finding out this bookseller is a girl) and finds her optimism reminds him of his deceased fiancee Myung Hee (Kim So Eun) who sacrificed herself while captured by Gwi.
The drama shows Sungyeol's struggle to keep his vampire nature in check by avoiding human blood on a regular basis and only drinking it when it is the full moon, thanks to the team work from his servants/friends Ho Jin and Soo Hyang. His ongoing interactions and growing feelings for Yang Seon often makes it difficult to stop the blood lust.
Another major part of the story includes scenes which show Gwi's involvement and power over the royal court which has been going on for many years and the ongoing fight to stop Gwi from taking full control. Sungyeol has been working in secret to take down the villain but also later enlists the help of the current Crown Prince Lee Yoon (Shim Changmin/Max from TVXQ) and many more loyal followers throughout the series.
There are some inconsistencies in the story-telling at the beginning and a ton of Kdrama tropes which would irritate a few viewers but it does somewhat improve (if you can also tolerate the odd CGI effects in places). Since I was reading the Manhwa at the same time as watching this drama it was interesting to see notable differences between the two versions and I believe the Manhwa was still ongoing at the time of the live adaptation being broadcast which does explain how there were changes in the plot, how a few characters in the Manhwa never appeared in the live action or had their roles completely changed.
Yang Seon's history for example is very different in the Manhwa. She had three older brothers who are all deceased after they were forced to drink poison. Jo Saeng is her adopted father in the drama but in the Manhwa he is a bookseller colleague though you could say he was almost a fatherly figure, albeit rather dishonest at times. I was just amazed with how in the drama, he managed to hide from his wife and daughter that Yang Seon was not his biological daughter and they only found out after his death.
Sungyeol's history was barely touched in the Manhwa though we know he was bitten by a priest vampire. As for his previous love life, no mention of that in the Manhwa either though in the drama we know he was in love with Myeong Hee. I also find him more playful in the Manhwa. I did not however appreciate how whenever he saw Hye Ryeong who happened to resemble Myeong Hee, he would just flip his character and turn cold towards Yang Seon after treating her rather sweetly. Make your mind up please.
Hye Ryeong's original plan to deceive Crown Prince Yoon in order to become Queen but eventually growing fonder of him was a big risk and I knew Gwi would not approve. Making it more risky was when Yoon accepted her despite this deceipt. I do feel they could have a closer bond if they met in different circumstances. Yoon really tried to also not become another puppet of Gwi and fight him like his ancestors did in the past. His childhood friendship with Seo Jin/Yang Seon almost mirrors how in the Manhwa said female was close to Moon Chi-san.
On the subject of the big baddie, Gwi deserves his own series. A prequel to outline his history with the royals as well as how he became the vampire we grew to like and hate (however appropriate), learning about humans. I actually liked his interaction with Hye Ryeong and you could see his regret from that accident near the final episodes when he tried to lure Crown Prince Yoon out of hiding. Asking Kim Sungyeol to hurry up and kill him...at least he had another layer of a character for a villain. Even in the Manhwa, I was fascinated by the backstory he had with the Crown Prince Sado. That friendship was unexpected. We didn't get that in the drama but at least there was his history with Hye Ryeong. If she didn't get offed like that, he would have turned her into a vampire too.
Ah there is much I would have liked to see in live action (Hoyun the hunter and his banter with "Glasses" aka Prince Hongjae) but I guess I will settle with re-reading the Manhwa and maybe re-watching this drama. Scholar Who Walks The Night may be cliche or predictable in a lot of the plot, but it still has enjoyable moments and of course like many dramas, the OST is great.