Bonus Material
Written by MSG Commander
When you load your game after reaching the True End, the game puts you back in the Realm of Swelling Darkness, about to go face the High Beast Lord.
Josh says Uranus is calling you all to him, and you should go see what he wants right away.
Exit the Realm of Swelling Darkness and go to the Other World through the distortion in Avis Gate. Talk to Lagomorph in the Forest, and warp to the Heavenly World. Now, go to Uranus' Castle and go north to the next screen.
Uranus is still concerned about whether or not Alia can be trusted not to give in to the High Beast Lord, but he says if you can defeat him in battle, then he'll say no more about Alia.
He says that first, you need to challenge the Guardian Beasts in the Square of Fate. There are three Guardian Beasts in the Square of Fate, each in their own side room. I don't know if matters what order you fight them in - I just went from left to right, through each room.
So, the first battle is against Lucius, who's in the room all the way to the left.
Lucius

Recommended Level 85
62000EXP/4800G/10CP
Drop: Muscular Strength Seed
Reward: Certificate of Courageousness
It might take more than one attempt to beat Lucius, regardless of your level.
In order for this strategy to work, you need to equip 4 Feather Amulets onto each Guardian Beast, and set all your beasts to "Guidance." It also helps if you can max out the weapons and armor for Kline, Alia, Fred and Vil (ideally, you should max out everyone, but Anne and Paola's weapons are a pain to strengthen.)
Before you start the battle, equip Fred with All-Reflect, and Kline with All-Shield.
On your first turn, use All-Reflect and All-Shield, and have Alia use Brave Heart. Then on the next turn, use the Linked Skill Deadly Rain.
Now, continue to use All-Reflect each turn. Have Kline use Black Flash Oblivion Blade or Ghostwail Slash, and have Alia use Energy Flow along with the occasional Holy Breath (when you know everyone's HP is okay.)
Re-cast All-Shield as needed, and if Fred or Kline dies, use Energy Revive to bring them back.
When Lucius is almost dead, bring in Paola, Vil, and Anne, and use Ignis Carnage (which will hopefully finish him off, but if not, go back to Kline, Alia and Fred, and keep using the same strategy.)
Baron

40000EXP/12000G/10CP
Drop: Vitality Seed
Reward: Certificate of Protection
After beating Lucius, go back to Laft or Illumica and raise your Assault Gauge back to 100%. Then come back and challenge Baron.
Again, use Kline, Alia, and Fred.
On your first turn, use All-Reflect and All-Shield, and have Alia use Brave Heart. Then on the next turn, use Deadly Rain. Follow this up immediately with Paola, Vil, and Anne's Ignis Carnage.
Now you can keep using Kline, Alia, and Fred, or you can swap Alia for Vil. (You shouldn't have to do too much healing in this battle - his attacks don't do a lot of damage.)
Have Kline use Ghostwail Slash, Fred use Swiftflash Dragon's Fang, and Vil use Mighty Lance.
Occasionally, Baron will use Impregnable Spirit, which will greatly reduce the amount of damage he takes. I couldn't find a way to remove that, so whenever he casts it just use your regular physical attacks.
The key to this battle is to just be patient, and keep hitting him with the strongest physical attacks you've got.
Grace

39000EXP/20500G/10CP
Drop: Spiritual Strength Seed
Reward: Certificate of Affection
Okay, this battle is literally a joke.
(As in, it's so easy to win, even a caveman could do it.)
Don't even bother with filling your Assault Gauge before this battle; it's not worth the extra time and effort.
As soon as you're done with Baron, come challenge Grace.
Have Kline use Black Flash Oblivion Blade on every turn, and if he runs out of SP, use an Energy Cube to refill it.
Use whoever else you want, and whatever other skills you want, but make sure Kline uses Black Flash Oblivion Blade, and make sure he's partnered with Rooselevy.
Then just sit back and wait until Grace is dead.
Uranus

Recommended Level: 95 or higher
80000EXP/0G/10CP
Drop: Magic Power Seed
Reward: Certificate of Brightness
Once you've defeated all three Guardian Beasts, now you can face off against Uranus.
Before you do, make sure everyone's Assault Gauge is 100%, and equip all of your Guardian Beasts with 4 Feather Amulets each, and set them to "Guidance."
Also, raise each party member's armor to the highest possible level. Give Fred and Anne Holy King's Armor, Paola a Holy Robe, and Alia a Dragonscale Dress (you'll need to buy a Silk Dress in the Weapon Shop, and then strengthen it.)
Make sure Kline has Ragnarok +5, and then strengthen everyone else's weapon as high as you can. Equip the Goddess Eye, and the two Goddess Amulets, and then buy three Soulreader Amulets, and equip them to your other three party members.
Now you're ready to challenge Uranus - but be warned, even at level 95 it may take more than one attempt to win this battle.
On your first turn, use Kline, Alia and Fred's Deadly Rain. Then follow that with Paola, Vil and Anne's Ignis Carnage.
Now put Kline, Alia and Fred in your party, and have Fred use All-Reflect every turn, and Alia use Energy Flow. Have Kline use All-Shield as needed, then the rest of the time use Black Flash Oblivion Blade. (Again, if Kline runs out of SP use an Energy Cube to refill it.)
Uranus will use Vengeance a lot - and when he does, you need to use Curealls immediately to remove the effects. Otherwise, Fred's turn won't come until after Uranus - at which point All-Reflect becomes entirely useless.
All-Reflect will work against both Aerial Slicer and Splash Blaze, which Uranus uses a lot, but not on every turn. Still, you want to use All-Reflect every turn, just so you're ready for when he does use one of these skills.
His other skills can do a lot of damage, and occasionally he might kill one or two part members, so you need to make sure that Kline has a Reviving Breath Stone with a high Resurrection skill. Also, it'd be good to give him a Healing Breath Stone with a high All-Cure Full.
Of course, sometimes no matter what you do, Uranus will kill your entire party. And sometimes he'll kill two people, and you may need to change your entire party around, and try a different strategy to finish the battle.
The strategy here will not work every time, but it works better than any other strategy I tried, so if nothing else it's a good starting point.
Once you defeat Uranus, you've essentially finished the game (although if you want to, you can fight him and the High Beast Lord over again, as many times as you'd like).