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16 - Letter #15: Hayato’s Fourth Letter
Map Coordinates: X: 471.5 Y: 417.9
When you reach his point, look for the group of rocks and a small patch of water of the map. Jump down through the opening in the center of the rocks to find the body down below.
17 - Letter #20: Hurk’s Fourth Letter
Map Coordinates: X: 497.5 Y: 500.5
Walk to the road that is mapped to the north of the letter marker on the map and you will find a bunker there. Go through the door and follow the stairs on the right. Continue around the corridor and you will come to the body lying on a bed.
18 - Letter #14: Hayato’s Third Letter
Map Coordinates: X: 602.9 Y: 457.6
Just north of Turtle Hill on the far east side of Thurston Town, you can easily find the bunker to the east of the road. Enter the bunker and find the body to the right.