I thought of a manga premise: someone who works at a hitman organization but is an accountant or something and is innocently unaware of the dark side of the company or that all their coworkers are hitman, cleaners and murder R&D types but still has a close working relationship with them, not understanding the code words or phrases they use and not thinking they mean it literally when they mention killing people, and in turn their coworkers like hanging out with them since our naïve protagonist reminds them of the innocence they lost when joining the company of death.