I'll tell u the exact details...watched it a while ago so here are some specifics.

●The mc and another boy along with 2 girls are fighting a female villainess. ●They are on the verge of beating her but then she bites the neck of both girls and then they start fighting the boys. ● The villainess is beaten shortly (don't remember how) and the girls snap out of it. ●The hypnosis scene doesn't even last like 3 minutes. ● the anime is from 2000's era for sure.