It'll be easier to pursue a new guy on a new playthrough, I'm not sure if it's even possible to have more than 1 per playthrough. In my opinion though, Tocchan was the easiest to court as you have access to him very early in the game.
So i'm pretty sure that i'm gonna finish the game single. But i've heard that you get stuff that helps you if you decided to do another play through is that true?