Right after the scene where Senel and Chloe train in the woods, talk to the automaton just outside Maurit's Hermitage. The robot only speaks in binary. If you run the binary through a binary-to-ASCII converter, it reveals the names of the game's QA Testers.
After beating the entire game (including Character Quests), save your game and then load that file to open up the GRADE Shop. The GRADE that you earned during the main game adds up, and you're able to purchase extras in here that come into effect during your next playthrough. Titles are automatically passed to your next game.