A story about either Naneal, Airi, or both desperate to pee.  

For Naneal, it could be that she decided to drink some of the milk from the bottle she was carrying, and an adverse side-effect is that it acted as a powerful diuretic.  

For Airi, it could simply be a case of her trying to escape from her opponent so that she can find a place to pee.

Those are just some ideas I thought up.  The only real requirement for this challenge is for Naneal and/or Airi to be desperate to pee and in search of relief.  You can even add other Queen's Blade characters in if you want.  Oh, and they get no enjoyment from their predicament.