Adam is a host club in Kamurocho.
Kazuma Kiryu becomes a host here in order to become #1 and change the club's culture of treating its hosts unfairly. This starts a lengthy side quest in which Kiryu trains himself in the art of hosting by doing various jobs from being a barker, to taking clients out on dates. In Yakuza Kiwami 2, this side quest, along with the associated hostess club management at Marietta, is replaced by the Cabaret Club Grand Prix side quest. The location still exists however.