nice design! why can't lock enemis?
You can choose which enemy you want to hit by clicking on it -- assuming its on-screen. Large mobs may have one or more enemies out of sight, attackable only when all the rest are dead. Of course, if your characters Lust Break (as they inevitably will), they will tend to start ignoring your input and do something random instead, at which point, just click anything because it just doesn't matter any more ;)