The SOP Shop
Written by MSG Commander
Special Locations
There are four Special Locations you can buy in the SOP Shop. Each of these is covered in detail on its own page:
Extended Scenarios/Characters
Here you can unlock two additional party members and an additional battle in Granzalk Garrison Post. You can also pay to raise the Merit Points maximum level to 10.
Useful Quest Items
Here you can buy some pretty cool items and accessories to help you in the game. (Most of this is unnecessary, as even on Hard difficulty, only the last few Boss battles are really hard.)
The few items that I do recommend are the Amulet of Mystery, Orlov, and Lapis Lazuli.
The Amulet of Mystery will protect against all Abnormal States, Status Drops, and Sudden Death, and will be extremely useful in the latter stages of the game. Throughout the game you will also obtain one Unicorn Amulet which protects against Abnormal States, so you can get by with 3 Amulets of Mystery, but if you've got the points, you might as well buy 4 of them right off the bat.
Orlov gives you an extra 50% EXP from all battles, so it's really useful for grinding. If you're on Hard mode, you will need to do a little grinding near the end of the game, but otherwise you don't absolutely need this accessory - it just comes in handy.
Lapis Lazuli gives an extra 25% gold from all battles - which will become important after you've completed the normal game. In the Bonus Material, you will acquire some really cool weapons - but at Lv6, and you will ultimately want to reinforce these weapons to Lv7, and that will cost a LOT of money!
(Note: You do also get one Lapis Lazuli just through playing the game, but you can stack up to four of them, so buy as many as you're comfortable with.)
The rest of the "Useful" items, well, they can be useful - but in my experience they're not really needed.