Ability to resist certain choices that the MC would otherwise be very inclined to make (e.g. seducing the centaur into mounting him if too slutty)
I'm honestly unsatisfied with the Willpower system as it's currently implemented.
it should be a regenerating-over-time(days) resource, its amount inversely proportional to Hiro's sluttiness and should be used to resist failed slut-checks so to avoid inevitable automatic defeats and gameovers.
Like, you start with 10 willpower regenerating 1\day.
You get the know a lot of times, the total willpower lowers to, say, 7.
If you get to the point you'd get knot-end because you fail the know lover check, you can spend 1 willpower to avoid it.
The lowest max Willpower should be 1, with very few encounters like Dark Knight requiring directly Willpower and\or in addition to normal checks.
Generally speaking, the idea is that one should be able to survive Slut-check Gameover at least once a day even at the sluttiest.
Obviously, if you fails the check and have no willpower left, then you get the game-over