Cyberdimension Neptunia: 4 Goddesses Online (EP)

This one will likely be one of the last trophies you obtain. For me, it unlocked while doing Rank 8 quests but you can speed up the process by equipping Silver/Gold Gems or using the "Eye of Providence" item to increase the amount of money you obtain in dungeons. Keep in mind that this is cumulative so you don't have to save your money and you can check your progress by checking "Various Records" under the "Adventure Diary" menu option.