Unsure cause your descriptions a bit vague and heaps have a similar trope but these 2 kinda sprang to mind? more on the black haired one being new to the job/scares people off?
https://www.mangago.me/read-manga/kocchi_muite_waratte/
https://www.mangago.me/read-manga/konbini_kun/ reply
Can only think of this one off the top of my head. He kinda alternates between messy and not messy. https://www.mangago.me/read-manga/fushidara_na_hanatsumi_otoko/ reply
did song lyrics stuck in head
