Tantei wa Koi wo Shinai

From Manga Abyss:

During an undercover operation, female detective, Ui, met her childhood friend, Naoto, again for the first time in years. Due to the trauma from an incident in the past, Ui has had a lot of problems sleeping, but for some reason she fell asleep in Naoto's arms. She's supposed to have decided not to love again, but Naoto's straightforward eyes cause her heart confusion...? The beginning of a story about a childhood friend's wholehearted love with a bluffing woman detective going forward, body and soul. It's a stylish kind of love story.