Here's a clean, Webnovel-ready edit with only formatting, grammar, and minor flow fixes. I did not change your plot or dialogue.
Chapter Title Suggestion:
"The Collision That Changed Everything"
Haesoo exhaled slowly and continued walking, her thoughts drifting back to her conversation with the inspector earlier.
Suddenly, a figure collided with her, causing her to trip and lose her balance. She landed hard on her butt and winced in pain.