Joker

Joker (ジョーカー) is the antagonist in Emelia 's scenario in Saga Frontier.

Story
In the intro of Emelia's story, he's the one to murder her fiance Ren, however Emelia is the one to be thrown in prison. He then keeps re-appearing during the story as it progresses, however he's never an in-battle opponent.

SPOILER WARNING AHEAD:

At the end of the game after the final boss battle, it is revealed that Joker was Ren this entire time, he just wore a mask which possesed him. One confusing thing about this is how anyone could think Ren was dead if he was wearing the Joker's mask all along.