Instructions
Play through the campaign mode of the game until you meet the character named Blister. After talking with Blister, leave the building where you meet him and go outside. Go past the shops and doors here to the right until you run into a child standing in the street.
Talk to the child. He will challenge you to a structured deck duel. Select "Yes" to accept the challenge and choose a premade deck to duel him with. You must defeat him in order to continue, so if you lose, try again. Once you defeat him, he will ask if you want to play again. Select "No" to exit.
Go back down the street and enter the door to go to the building where you met Blister. Go up to Blister and talk to him again. He will explain that you will be able to sneak into a building and get back some of the items taken from you earlier in the game.
Continue to talk to Blister and listen to his plan. At the end of his speech, he will give you a fake security uniform and a fake ID card key that you will need in order to sneak into the next area of the game. Equip the two new items in order to use them.