Unbeknownst to Izma, her corruption gives her a subtle aura that allows her to influence those weaker than her to submit to her. If the PC loses multiple fights to Izma, they become increasingly submissive to her; if they accrue too many losses, then a Bad End is triggered in which they give up on their mission and become Izma's beta, and, it is implied, the first shark girl/tigershark in her harem.
However, this aura's effects are very weak; achieving one victory in combat against Izma will counteract the effects of one defeat.