Opposite the Eden entrance you will encounter a kid looking rather depressed as he watched another kid with his father. This kid has lost his father and has no friends to play with, thus Kenshiro is tasked with being his play mate.
The kid wants to play Hide and Seek. He isn’t too difficult to find but in order to find him you first need to travel to the area above the Gate.
In order to do this you must speak to the guard who is hiding along the wall to the left of where you activate the quest, he will grant you passage to the area above via the Elevator.
After stepping off the Elevator immediately turn around and hit the ‘R3’ button to zoom in and the kid should be sitting above the Elevator door.
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