Go to Feasterra on the map, enter Horace's house in the second section of Feasterra, and there's a dog house inside the room.
I was not able to find the cookie in the doghouse.
Have you finished the fight with Grant X and finished the main story for this update. You can't get it if you haven't finished it first.
Not yet. =/
I need to improve my skills to the fight =)
Thanks
