This article is from the Final-Fantasy and other Square Soft Games FAQ, by email@example.com (Nick Zitzmann) with numerous contributions by others.
You technically can't, because it's never lifted totally until Lavos is
But anyways, if you want to see it, defeat Magus twice, then defeat
Lavos. Frog will now be Glenn again, but you won't be able to get the
secret character if you do this.