Some rlly good ones are:

Shutline -40+ chapters, ongoing
Define The Relationship -33 chapters, ongoing
My High School Romance- 53 chapters, ongoing
The Pizza Delivery man and the Gold Palace- 29 chapters, ongoing
Exploratory Battle- 5 chapters, ongoing
When The Killer Fall in Love- 22 chapters, ongoing
Interview with a Murderer- 53 chapters, completed
Semantic Error -52 chapters, ongoing
One Take -52 chapters, completed
Stakeout -34 chapters, ongoing
The Third Ending -56 chapters, ongoing
Too close/My Dear Nemesis -180+ chapters, completed.  But I recommend reading it on another site because the translators cut out several scenes.