KAKU: Ancient Seal Launch Exclusive Content includes one piece of gear: Ancient Attire, one Old Kaku Gold Statue (in-game), five High-Definition Wallpapers, and one Concept Art Book.

Q: Where can I find the DLC contents(Wallpapers and Concept Art Book)?
A: Select KAKU: Ancient Seal in your Steam Library, right-click and select Manage. Then choose Browse Local Files to access DLC contents located under the 'KakuAncientSeal\Launch Exclusive Content' folder.