To earn Qi Gems, you’ll need to complete challenges on Mister Qi’s Special Order Board.
Qi Gems are used to buy some pretty amazing end-game items. Inside this mysterious Walnut Room is Mister Qi, an NPC that rewards you with Qi Gems for completing special challenges. This is the Walnut room and you can unlock it once you collect 100 Golden Walnuts. Located on the far West side of Ginger Island, you’ll notice a small door that leads to a secret room.
One of the late-game secrets in Stardew Valley, which arrived with the 1.5 Update, is the Walnut Room. Here’s how to unlock it and what’s there. Stardew Valley Update 1.5 is filled with secrets, including the Qi’s Walnut Room on Ginger Island.