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That'd be the "Shopkeeper". 

Keep spending at the shop until you see your money go negative and attempt to leave the shop.

It's on the main menu. New unlocks come through playing the game and using the "dominate" button when it pops up. It unlocks scenes that you haven't seen for a dominated enemy.

Update: same with "Tongue Kiss" dealing 4 lust, not 5 as stated in text.

Found bug or unintended text.

The skill "Flash" describes granting 3 lust to all enemies.

It only grants 2, not 3.