[Scene 4.2] Queen of the Red Storm: On the way to meeting up with El your guys run into more Drake units. Defeat Miyugi +1 Skill.
[Scene 4.3] The Base of Silence: Shila's Castle is being seiged. Defeat Geriel and Alen before Ban's Reinforcements arrive (around turn 4 or 5) +1 skill. Your guys learn that the only way back to the surface world (earth) is to go meet Skily Mau. However Drake is currently holding Skily Mau, so your guys decide to make their move.
[Scene 4.4] The Forced Open Path: Your Guys begin your assault on Drake's castle. But you'll have to go through his entire forces. Around turn 5-6 Arufimi appears through the aura road! But then so does Tobikage (wtf?!) Defeat Arufimi +1 Skill. After the Battle, your guys waste no time heading back to the surface world.