The Wacky Adventure of Rhys Walkthrough
You start the quest standing outside of the ruined town. Go inside and talk to the soldier. He thinks you're some guy named Nial and tells you to enter a cave to the south. Head south to check out that cave, you won't need a gem to enter it. Follow the passage until you exit in Elysium. Use your monitor to get a good chuckle.
Head south to the town of North Divisia. Continue south into the castle. Everyone there claims they kidnapped a Layan named Alair. Hop into the castle dungeon... It looks like Alair found her own way out. Oh well, continue through to South Divisia. In South Divisia you learn that some rebels are in a southern cave... Let's go check them out.
Work your way to the cave. Inside you'll meet Ryan... who is disguised as Lyle! Talk to Ryan/Lyle and Lune will appear... After some threats from Lune, Ryan/Lyle will join your party.
Look at this... It turns out Mieu was actually disguised as Ryan who was disguised as Lyle because she's now in your party. Grab the Sub Parts for Wren while you're there. Haul all the way back to Satera town in Landen... Go as far North and East as you can so that Landen castle is clearly in view. Hack the save state so you're standing just below Landen again.
Travel down to Ilan and talk to the guy who tells you he saw a Layan. Head up to the lake and talk to Mieu. Wren will join your group now. Go to Yaata and talk to the boatman. Sail to the island. Go into the island cave and talk to the real Lyle... to get the Sapphire. Leave the cave and journey east to the passage to Aquatica... When you arrive head south towards the passage to Aridia. Hey, you remember those Sub Parts? Are you thinking what I'm thinking? Go hop into the whirlpool to get Lyle.
Leave the whirlpool and head west to the cave where Wren is. As you probably figured out already, Lena will join your group when you talk to Wren. Head south into the cave that leads to Frigidia. Although you do not possess the Mystery Star you somehow use it to enter the passage.
Haul all the way down to Mystoke and enter the castle. Fight your way to the throne room with Laya's Pendant... Use it to hear Laya's final words. You can now easily travel between worlds!
This is basically the end of "The Wacky Adventure of Rhys". If you go to Aerone and try to take the shuttle to Azura, the game will freeze. If you can take this quest further I'd love to hear about it!