Orobashi's Legacy Part V : Yashiori Island
Completing this quest will give you "Kitain's Cross Spear" blueprint. To unlock the water dome, you need to realigned them all until last pillar shoot to the dome. You need to use the ship.
After killing this Maguu Kenki, you need to take one item behind the ward, and the item right on top of the ward. I was confused at first. Until I realized it just on top of it.