Devianne:
The volunteers have finally come! There are many Embryo soldiers around who guard the Stronghold of the Messiah Castle. Your task is simple: destroy the Embryo Castle Siege Tank or the Embryo Castle Magic Cannon of the Stronghold. After you destroy the mechanism or the cannon, one of the Embryo Commanders will appear.
By the way! Embryo's soldiers hid a Sayune nearby, which is used to transfer reinforcements. If you kill the Embryo Commander the hidden Sayune will appear. With this Sayune, you can move on. Well, good luck.