I defeat the final boss located at the top of the Chrysler building in the first EX-Game play through and show the second ending of the game.
To get this ending you will have to beat the normal game once and then start a new game in the “EX-Game” mode. Near the end of the “EX Game” I go after the Chrysler building before encountering Melissa (Eve) on the top floor of the museum, which would normally usher you into day 6 without a point of return. At this point you can spend time leveling up in the re-occurring battles in the museum and gradually work your way up to floor 70 in the Chrysler building. The last 7 floors are not inhabited by enemies and serve only to create some suspense on your way to the final boss.
I basically conserved all of my bonus points from both rounds until the end. I also stored away all of my weapon and status upgrades that you get throughout the game. At the end right before the final boss I transferred all of my extra attributes onto my current weapon and armor of choice. I made sure I got all 14 rare trading card types for Wayne in the police department so you can get infinite super tools from a Super tool kit. Once I had this I was able to transfer over all of the plus attributes of all the stored unused armor and weapons onto one item. After that I rattle off most of my bonus points into the attack parameter for my pistol to make the final battle go a lot quicker.