Uh? I don't think KP has any scenes that are locked by difficulty, although playing on Secretary makes it hard to "lose". I think Warden is the right balance for a new player especially.
The fastest way to unlock more scenes for me was losing in the hard difficulty and raising the slut level as Losing is easy in hard.
Then play normally with all the sex options unlocked.
Btw I don't think there is golden shower in this, there is only rimming, anal, vaginal, blowjob, gangbang and bukkake.