I can say with confidence that probably about 90% of females living in Korea over the age of 13 is watching this right now. I bet they are also searching and watching videos related to 변우석 (the male actor who is playing the character 선재). 

I can also say with confidence that people are probably downloading or searching the soundtrack and listening to the song 소나기 sung by 변우석!

Cause I've been doing that too!

This K drama that is viral right now was originally created as an online novel.

The original novel was called 내일의 으뜸.

I read it and the original is a bit different from the TV drama. I can tell you that for sure.

HOWEVER, they both are amazing and awesome.

There are the pros of reading a novel and then there are the pros of watching something visually.

They both have different approaches but I think they both represent the original purpose and values the author had.

I can bet that many many boys are going to sing this at 노래방. LOL