Actually, second class does need RPGM, but thats because of the outfit system. Keep in mind a lot of dialogue is dictated by what you choose to wear/accessorize with. Ren'Py can't really do the same thing, plus the outfit changes are also kept logged so as to also help with progression into certain areas. Like if you dress like a sissy, you'll get treated like a sissy, and even if you change your outfit, it will be remembered you were into sissification, or at least crossdressing. It hasn't gotten super far yet, but that's always been a big theme of SC, so...yeah. I actually think RPGM is the correct choice, especially since its being utilized in an unusual way