Good chemistry and romance but not as the main plot?  Or just hints of romance

Ex - Unnatural, Ouroboros, Mr. Queen, Flower Of Evil, Nobunaga Concerto 

Note : No slice of life themed dramas

Love Me If You Dare (mystery, detective, a bit of romance)

mia noi (it's really about luxury prostitution and abuse, but there's a running thread of a romance. Highly recommend it)

The Queen of Office and Ms temper and Nam Jung Gi both about office politics with some romance. 

Liar Game  (Some people see the romance, others don't. There's definitely some sort of affection)

The Good Wife (J-dorama): The romance is much, much more subtle than the korean and US versions. The cases are also more interesting in my opinion. 

The One and Only - Fl finds out she has inoperable brain cancer and that she is going to die in a few months. She checks into a hospice where she meets two other women, and they decide to kill someone who deserves to die, before they die. When they do they run into ml who is a contract killer.

Lie After Lie - Fl gives birth to a girl in prison. 10 years later when she gets out of prison, she decides to track her daughter down. Upon realizing that her daughter's adoptive parents are divorced, she decides to seduce the adoptive father to become her own daughter's stepmother.

Mr Sunshine - Takes place at the beginning of the 20th century. Japan has a strong military presence in Korea and the fl joins a group of rebels to try and regain control of the country. She meets the ml who is an american officer who fled from Korea as a young  boy.

You are all surrounded - nice mixture of romance+thriller+crime

Hello Harinezumi - mystery comedy with a detective agency that solve various cases. Each case has different genres. There is also some romance, but it is not the main topic.

The Legend of the Condor Heroes (1983) - The main genres are wuxia/action/adventure, but there's also a lot of romance.

- Crossfire -  Gaming x fiction x slight romance

- Vincenzo - Crime x Law x slight romance