There are a total of 16 God Chests. God Key is dropped by Key Orbling in Shangri-La.
God Chest #1
Item: Light of Judgement
Location: Shangri-La - Bridge to the City, on the right side area of the bridge.
God Chest #2
Item: Alexandrite
Location: Shangri-La - Fallen City, west area.
God Chest #3
Item: Deus Augite
Location: Shangri-La - Fallen City, east area.
God Chest #4
Item: Ruby XL
Location: Shangri-La - Fallen City, northeast area.
God Chest #5
Item: Fairy Rod
Location: Shangri-La - Fallen City, in the middle of the map.
God Chest #6
Item: Colossal Blade
Location: Shangri-La - Sanctum, west area just before the boss. You'll need Durable Ivy to the access the chest.
God Chest #7
Item: Siegfried
Location: Shangri-La - Sanctum, west area just before the boss. You'll need Durable Ivy to the access the chest.
God Chest #8
Item: SP Capsule x2
Location: Hidden Valley - Bernard's Laboratory, F2.
God Chest #9
Item: Megaton Punch
Location: Hidden Valley - Bernard's Laboratory, F2.
God Chest #10
Item: Hyperspace Ring
Location: Communication Network, north area of the map just before the boss.
God Chest #11
Item: Elixir x5
Location: Sanctum - Mirror of Order, at the split paths.
God Chest #12
Item: SP Capsule x2
Location: Sanctum - Mirror of Order, at the split paths.
God Chest #13
Item: SP Capsule x2
Location: Sanctum - Mirror of Order, at the split paths.
God Chest #14
Item: Deus Augite x3
Location: Sanctum - Mirror of Order, east side area.
God Chest #15
Item: Deus Augite x3
Location: Sanctum - Mirror of Order, west side area.
God Chest #16
Item: Deus Augite x5
Location: Sanctum - Mirror of Order, east side area access from the west side.