Jiango is the creature that the guards of Hellena Prison used to punish prisoners. They feed the worst prisoners to this creature in hopes to frighten the others. The party defeats this creature when they get captured in its lair the second time they return to Hellena.
The battle with Jiango in Hellena Prison can be difficult. He has powerful physical attacks, and has the ability to confuse a character. Wind-based Attack Items and other magic can help immensely in this battle. At the beginning of the battle, using the Sachet that you should have gotten from the chest earlier will put the Jiango to sleep for a certain number of turns. While he is asleep, attack him with all your might to defeat him as soon as possible. Don't use Dragoons while he's asleep, because then you can use them after he wakes up, aiding your defense and protecting against his Confusion. After what could be a difficult battle, Jiango will be defeated.