Hello! I'm looking for korean drama or movie where one of the male protagonists (or an important secondary character) while basically a good guy is responsible for a death of another character and some sort of tension arises from it.

Basically looking for a character like Koo Dong-Chi from Pride and Prejudice or Windmill Man from Baking King.

Not looking for a Dexter-like character.

Thanks!

Ugly Alert is exactly what you're looking for. It's very long, but it's all worth it :)
i agree with Iwyn ^, Ugly Alert is definitively worth the watch ♥
Thank you, guys, I'll check it out! :)
There are only two that come to mind straight away, namely, 'Crazy for You / Crazy for Love' and 'Sang Doo, let's go to School'. But there are 2 others where the protagonists take on the guilt of somebody they love to protect them, only to find that their love and sacrifice were misplaced. In 'Innocent Guy' the main character then sets out to get revenge whereas in 'Secret' the lead female is further cruelly haunted by the lover of the women she purportedly killed. 



Ugly Alert or What's Up =)