Y/n was shopping at a luxury mall and found the black card. She didn't know it was his and was just surprised she found it. She looked at it for a moment before putting it in her purse, not knowing that she had just failed the test

you slip the card in her purse, and wait to see what she does

Kaori doesn't even notice the card, and instead is just shopping, buying herself a few things and Taehyung some gifts