The Cafe Down Below [BSD]

Raised in the Mafia, the infamous mystery 'White Reaper' was given a time-off away from work by the Boss.
Not knowing what to do, the boy found himself a job at a cafe which so happens to be on the ground floor of the ADA.

Or

Mafia Atsushi mets the gang in a different way and chaos ensures when a certain Sudical mania fell for him.