Go to Delta : Fly Away Marble's Pinwheel.
Use Fairy Orb, and go to a room where it has 3 chest.
You can only find the Doppelganger after level 8. Beware, the Doppelganger is extremely powerful. He has all the skills you have, has the exact same HP and SP as you do, but he is 8 levels higher than you and all his stats are higher than yours except for HP and SP.
I recommend you fight him at the end of game when all your characters are at level 50. I also recommend going to an area where the Lucky Animal Sleipner is located, like Essential Red Plum's Resort. Find Sleipner and kick him. Now wait 10 minutes, don't do anything, don't even touch your controller.
When 10 minutes is up, go wander around the field. A red arrow will point towards the Doppelganger when you are near him. A message will appear on screen, then the edge of your screen will be cloudy. Run toward him and activate a fight. Right when you start the battle, Sleipner will come in reduce Doppelganger's Health by half.
Now use Beast Awakening, be sure you have Silabus and Piros for this to work effectively. Equip a broadsword and he should go down in no time. However, he is able to cast spells to heal himself, and he is constantly regaining HP and SP throughout the fight.
By defeating him you get the Own King, a Key Item that transforms in one of the later volumes.
Go to Piling Red Plum's Twin Rocks. If you rotate the camera from where you warp in you will see (if there is one, since they dont always appear) the battle area. I have three of the blacklist completed and i got them all here. Also if you look closely you can see the water drop above Mecha Grunty's head from where you warp in. There are also two Chim trees within sight of each other that if you run from one to the other, and dont get too close the the monsters, are basically free chim. (Kick one tree, kick all chim, run to other tree, kick chim, repeat and the chim respawn).
You are able to constantly farm the Beginner's Text and Beginner's Book from Corporal Yano and Henako constantly throughout the game. All that you have to do is find them if they are in Mac Anu and if they are, trade for the items and then enter a shop (Such as Weapons Shop or DX Weapons Shop), then exit the shop, and most of the time they have the items again.
At the title screen, select the Convert menu. Selecting save data from .hack//Infection, Mutation or Outbreak will give you an email from BlackRose that was sent to Kite after Quarantine. Selecting .hack//Quarantine save data will give you the previous email, and an email from Hokuto(.hack//AI Buster) sent to Rena(.hack//Legend of the Twilight Bracelet).
Must have Vol.2 G.U. Clear data already saved in memory card, by starting a new game in Vol.1 G.U. you'll be ask if you want to start at higher lv. select yes. Even after you get data drain by kite you stay at lv.35 instead of lv.1. You will also start out with stronger items, weapons, armor, gear, to match your lv.35 character. You can still Convert data from the original . hack games to get the bonus mails, before you start the new game.
On the desktop, hold R1+R2 and push square, triangle, square, triangle. Release the R's, then while holding L1+L2, push right, up, right, up. Release and press R3+L3. If you do this quickly enough, the Vol.2 Preview will become viewable in the media performer.