Ancient Training Ground
With the Enchinda dead, all of the black fog has cleared from the forest allowing the normal form of travel to resume. This area contains three red orb eggs and a new enemy, the fault. Faults will pop up underneath you and swallow you. They are easy enough to kill or just avoid.
There are two mephistos and a faust haunting this area now. Use Gilgamesh on them after removing their cloaks as it is a good opportunity to experiment with it without a risk of taking too much damage.
Another red sealed fight. The opposition this time is handful of assaults and a blitz. There are multiple stashes of red orbs hidden in the chimera eggs scattered about this area.
A third successive fight, this time against five chimera, two scarecrows and three assaults. There is nothing else to do here except collect the red orbs.
This area is bursting with red orbs. There is a large cluster next to the log, use the Devil Trigger and the Gilgamesh combo Kick 13 to maximise the orbs received. The log itself is full of red orbs and there are some more at the side of the pathway. Leave the forest now and go back along the bridge.