|This article is about a/an villain base in Ninja Sentai Kakuranger.|
Skeleton Castle (ガイコツ城 Gaikotsu Shiro) is the floating skull-like fortress headquarters of Daimaou and the Youkai after he abandons the Youkai Mansion upon the defeat of Daradara. The fortress has an appearance similar to Daimaou's own head, only overlayed with precious stones. The only room within the castle is the "throne room" where Daimaou continues to watch over the battle between the Youkai forces and the Kakuranger, with the statue-like form of the transformed Hakumenrou usually standing by his side as an ornament.
After the death of his sister Yama-uba and the Kakuranger's final redemption of Hakumenrou, Daimaou tries to perform a suicide attack upon the team by crashing the Skeleton Castle towards them; the attempt fails but he survives due to his own nature as the immortal embodiment of all hatred.