To unlock this achievement without having going through Story mode a second time, acquire amemory card and a hard drive. With a completed saved game file on your hard drive, start a new game on your memory card. Play past the training mission and save the game as soon as you get into the hotel mission. Then, quit the game. Load the saved game file from the hard drive and go to the final Boss. Go into the "Options" menu, then to the "Game Play" setting and change the "Memory" setting to the memory card. Defeat the Boss and the achievement will be unlocked.