Finding Yuffie
While roaming around a forest, you may run into a strange little named Yuffie Kisaragi. Yuffie is a female ninja and a Materia hunter.
Fuind Yuffie isn't always easy. You have to walk or drive around any forest area until you encounter her. Yuffie appears just like any other enemy creature, but she has the temporary name "Mystery Ninja". She's a tough fighter, but you should be able to defeat her without much trouble. Equip yourself so you're well protected against fire.
After defeating Yuffie, you'll go to a small map that has a save point. Yuffie is lying down here, but she's fine. Examine her and you'll start a long dialogue.
Tip:
If you want to figure this out on your own, you can't take your eyes off Yuffie. She's a thief and can't be trusted.
Warning:
If that morsel of info isn't enough, then read on. However, you must be warned that the following information gives everything away.
First, don't use the Save Point. Doing so means you must take your eyes off Yuffie and when you return to the main screen she'll be gone-along with some of your Gil. Second, don't insult Yuffie's abilities. She's a ninja and very pround of her skills. Third, don't do anything that might result in your losing sight of Yuffie.
Examine Yuffie and she'll challenge you to another fight.
Yuffie: "You spikeyheaded jerk! One more time, let's go one more time!"
Answer: "Not interested."
Now she's feeling cocky, so she taunts you. Talk to her again.
Yuffie: "You're pretty scared of me, huh!?"
Answer: "...petrified."
She'll start to leave, but turn back to yell:
Yuffie: "I'm really gonna leave! REALLY!"
Answer: "Wait a second!"
She seems to be getting the picture.
Yuffie: "You want me to go with you?"
Answer: "... That's right."
Yuffie: "All right! I'll go with you!"
Answer: "...Let's hurry on."
You've done it! From this point forward, Yuffie Kisaragi will be under you command.