Leaving for the New WorldPlaythrough/Route: 3/C
Quest: All Main Story Quests
Load a save that has achieved both endings A and B, then play through the game again (on the same save file) and complete all of the main story quests. At the end of the playthrough, you'll be required to select either A2 or 9S for the final battle. Choose 9S for this trophy, or choose A2 for the following trophy:
NOTE: Some people have had problems with unlocking this trophy. Though it's been mentioned that completing a quest has resolved this, I suggest saving as often as possible in a secondary save slot so that you're able to quickly attempt the trophy again.