There are 12 Zodiac Stones in Ogre Battle. Getting them is completely optional; however, if you'd like the best ending, you're going to have to get them all. It's not particularly difficult, but it could take ages, unless you know where they are. And to that end, this section was written. Here, I will assume that you have a grasp of the geography of all the stages I mention; if you don't, head over to the Maps section via the sidebar on the left and acquaint yourself with it. Also, you should assume that a high Reputation is pretty much required for this entire section, but if you're going after the best ending you probably have that covered already.

Before you can start gathering the Zodiac Stones, you'll need to get three items. These are the Gem of Doun, the Olden Orb, and the Gem of Truth.

The Gem of Doun: After beating the Pogrom Forest stage early in the game, return to it. There is a hidden city called Para in the northwest corner of the map. If your Reputation is high, you will be given Quicksilver when you revisit that city. Keep this item. Much later, return to the Dalmuhd Desert stage after you beat it. There is a hidden city in the northeast called Aliabard; revisit it and you will be able to trade the Quicksilver for the Gem of Doun.

The Olden Orb: After you get the Gem of Doun, return once more to the Pogrom Forest stage. Head back to Para and the same man who gave you the Quicksilver before will now give you the Olden Orb.

The Gem of Truth: First, beat the Ryhan Sea stage. Now go get the Gem of Doun and the Olden Orb. Now return to the Ryhan Sea; there's a city called Ramoto in the east. (It's not hidden, so finding it shouldn't be a problem.) Head there and, presuming you've got the other two items, you'll be given the Gem of Truth.

Now that you've got all three items, return to the Shangrila stage. Head to the capital (the city that used to be the enemy base), and you'll be able to exchange those three items for the Tablet of Yaru. Once you've got it, you can go hunting for the Zodiac Stones.

Amethyst: Visit the only Temple in the Dalmuhd Desert stage.

Aquamarine: Return to the Diaspola stage and visit the hidden city of Ajan, nestled in between three mountain ranges a bit southeast of the center of the map.

Diamond: Go back to the Ruined City stage. You'll be given this stone in one of the stage's two Temples.

Emerald: Head back to the Island Avalon stage and go to the hidden Temple in the middle of the island.

Garnet: Revisit the Slums of Zenobia stage and head to the Temple that's northwest of your starting point.

Opal: Go back to the Lake Jannenia stage and visit the hidden Temple east of the city of Allephal.

Pearl: This one requires a bit of work. If you've been through a city called Somyul in the Diaspola stage, you've probably met a little girl named Posha. If you visit that city with your Lord's unit before beating the stage, Posha will ask you to do her a favour. To do it, head to the hidden Temple in the south; you'll be given a Beehive. Return to Somyul and trade it for a Sentoul Demon (which you can trade for an Undead Staff in the city of Anglem in the same stage, by the way). Now Posha will ask you for a Ginger Cake. Wait till you beat the Organa stage, then return to it and visit the hidden Temple on one of the eastern islands. If you've got the Tablet of Yaru, you'll be given the Ginger Cake Posha wants. With the Cake, go all the way back to Somyul in Diaspola.

Peridot: Return to the Muspelm stage and go to one of the Temples.

Ruby: Revisit the City of Malano stage and go to Sanbelna, a hidden city in the southeastern quadrant of the map.

Sapphire: This is the quickest one to get. Right after you get the Tablet of Yaru in Shangrila, head to the hidden Temple in the center of the stage.

Topaz: Go to the Ryhan Sea stage and find the hidden temple south of your base.

Turquoise: Head to the Tundra stage and visit the Temple on the northern central island.

Now that all twelve Zodiac Stones are yours, return to the Muspelm stage and go to the city of Chilfa, in the northwestern corner of the map. There you will be able to exchange the Stones for a Royal Crown. Use this item on an Amazon and see what happens.