almost all of these kdramas are about investigation or mystery:
Bad Guys - this is one of my favorite kdramas! no romance, some criminals get together to solve cases
Gap Dong - police investigation, there's a female lead (i hated her -.-) but romance was not the main theme
Dr. Frost - if i remember correctly, there's no romance at all (but i've watched many years ago...)
Liar Game - an odd game, involving a mystery
Missing Noir M - it's a police investigation drama, it was not really my cup of tea, but you might like it, maybe...
Naked Fireman - this has a little bit of romance, but it's mainly about a mystery involving an arson case, quite funny and very short :)
Solomon's Perjury - it's about a trial organised by the students of a school
White Christmas - this! some students from an elite school remain at school during winter break and receive a letter saying that someone will die, really interesting!
not about investigation/police/mystery:
Tamna, the island - this is an historical drama set in jeju island, quite atypical and funny!
PS (i've written all the links, just click on the titles you're interested in :D)
