Instructions
Guide the protagonist to the room in the Aegis temple full of mummies and sarcophagi. Go to the next room on the right.
Follow the row of tombs until you reach a path. Follow the path until you reach a tomb with a bed and a bathtub.
Follow the next path behind the tomb. Follow this path downward until you exit the building and see a bird.
Tap the bird and pick up the Thief Map it drops. Open the map to activate the Bamboo Island mini-quest.
Retrieve the herb in the spice shop's store room for the mini-quest. In Aegis, deliver the letter to the female NPC who keeps you from speaking to her daughter, and the Shadow Thief outfit is yours.