Head forward round the curved path where the first boss, a group of Phantoms, will attack. After they are taken out, ignore the Green Crystal and head down the flight of steps to stone the gazebo, and battle the second boss, a group of Six-Wingeds and more Phantoms. These enemies can present a greater challenge than the group of Phantoms, so it's best to backtrack to the start to allow them to approach one at a time. In case they gang up and cause damage, use the Green Crystal to replenish some of Ayumi's health. Once the enemy scale is depleted, continue on course through the second gazebo killing any leftover Six-Wingeds that are still around and go inside the larger stone gazebo.
Here there will be a spiral staircase going down. Quickly head down to the platform, and take the three disembodied steps down to the final gazebo. Placed there are five Monster Generators on the path and four The Ancient Six-Wingeds from. The Monster Scale is for the generators, so focus on them while being careful to avoid the Ancient Six-Wings' Violet Ray blast and the constant swarms of Phantoms and Six-Wings. A good plan is to run the path striking each generator a few times in passing. Another is to run up to a generator and hack away, using a widespread attack like Fire Rage or Ice Flower when the monsters start to gang up. If the health scale becomes too low, run to the center of the gazebo where there is a Green Crystal waiting or if already used, take several laps around the path until it is refilled.
Once the generators are taken out, begin focusing on the four Ancient Six-Wingeds. The best way to kill these monsters is to head for the exit where there is a gap between the platform and the wall on the left that the monsters' Violet Rays can't reach. The best spell for these monsters is Fireball, as the Ice Arrow only temporary freezes the monsters. While in this gap, build up the health and rage scales, then hop back on the platform and attack the facing Ancient Six-Winged with a flurry of fireballs until the Rage Scale becomes too low. Then drop back in to the gap and repeat the process until this monster is killed. Continue this on the other two until they are all killed. After, go around and bust up the statues for extra souls, then enter the door where the portal is to return back to "The Ruins II", thus completing the Sky Islands.