Chapter 1 in the Machalania Forest where you find Tromell Guado at the water...all you got to do is talk to him 4 times and you will have it.
I got a question to you...is that the level of your girls when you try to fight to Mindy, Sandy and Cindy? If so, then it would indeed be wise to level up
And to fight to them, fight with two dark knights and a trainer to use HP flurry.
Also make sure you keep your HP high enough or when they use Overdrive...it's game over.