Really easy.
step 1. Play the game
step 2. When you get to Mid-boss, LOSE!
step 3. let the credits roll, then start a new game+
step 4. Go talk to her and she'll join your party
step 1. Play the game
step 2. When you get to Mid-boss, LOSE!
step 3. let the credits roll, then start a new game+
step 4. Go talk to her and she'll join your party