Baten Kaitos II: Hajimari no Tsubasa to Kamigami no Shishi Cheats

In order to rank up in the coliseum after rank 1 you must first complete all matchs in the rank you are currently. You must also have enough RP. After all this is complete, you will get a quest. To get the quest:

The Heartflask SQ is one of the most time consuming events in BKO. It is also necessary to do for a complete Magnus Gathering; and it goes through five different stages meaning five different Quest Magnus. The earlier you acquire it, the easier it is to complete this SQ. The Heartflask is given to you by Georg who can be found in the Nihal desert.

Thanks to GameFAQ's user OriginalHamster for helping to confirm the method of unlocking.

Once you defeat the final boss and watch the credits and remaining scenes, you will get the option to save. Save and you will go back to the title screen. Choose Load Game, and load your save file. You will start the game with your gathering intact.