Anyone who were a bartender, former and upcoming are listed here.
A bartender or barkeeper is a person who runs a local bars in any town, serving drinks and washing cups or dishes. They would pass out cola, sake, rum, or any other beverages, and they are also known to serve food. Makino is the first bartender seen in the series. Blueno himself acts as a bartender and owns a bar called Blueno's Bar.