Ryoji Mochizuki was one of the most interesting characters in Persona 3, and Persona 6 may be able to thrive with a character in a similar vein. There are a lot of things that Persona 6 can take from past games, from mechanics to character archetypes. In particular, Ryoji is a unique character in the series who managed to deliver in an impressive fashion. Persona 6's cast will need characters who can similarly strike a chord with players during the story. While Ryoji's gimmick was unique, it isn't one that can't be repeated with another character in a future game.