Ah, I see. I didn't know I had to lose the fight. I just used spells to lower her defenses and deal a lot of damage to win. Some of the party members got oneshot and defeated but I still managed to come out on top. Thanks for the help. Sorry for wasting your time.
No, the mistake is really mine! I should have made it clearer in the dialogue with Gigi. I really didn't expect anyone would be able to win that fight, haha. Congratulations! I think you must be the first. Enjoy and sorry for the trouble!