After completing Substory 9 – Hide and Seek. Minato will once again want to play Hide and Seek, this time he chooses a different spot to hide, no real surprise there. He isn’t exactly difficult to find, simply head towards the Casino.
He is hiding above the building next to the guy in blue with white trousers (he should of given you a substory or have a speech bubble above him). If you head to this guy look up and to the left and using the ‘R3’ button you should be able to spot Minato.
Related Guides / Links: