The castle is built atop a tall outcropping of rock that rises above a densely vegetated forest below. Tall rocky spires are visible in the distance.
Porcupine Castle is a conical tower, wide at its base and tapering to a point at the top. It features numerous protrusions which ring around it; possibly they are roofs or balconies. It is colored in shades of blue.
An attack on the castle by hot air balloon was made by Big Green when the porcupines to the air force hostage. Most of the balloons were downed, but First Squad successfully arrived at the castle. Subsequently, a sharpshooting contest between Lin Chung and Porcupine King was held on and around the castle grounds.