Don't be afraid to use sexy heroins NPCs at your campaign! It's an anime remember? There is only one problem though... an immature party, my fellow storyteller. You can handle your group better if you make one fall for your characters.
Female heroins make players have a reason to move forward to your goals, instead of a typical quest or mission, males tend to follow such a character without even any reward... Use a female type character that has some major features such as finishing each sentence with the word meaw, or even have certain tendencies as getting easily mad etc. Characteristics also such as pink or purple hair, remain easily in your player's head (along with a juicy picture you may have found in the web :P ).