Castle Dusk (キリ城, Kiri-jō), also known as Mugen Castle (無幻城, Mugen-jō, Literally meaning: Infinite Phantasm Castle, English Games "Mugenjo"), is the castle that appears in Naruto: Ultimate Ninja Heroes 2: The Phantom Fortress. It is also the main plot of the game.
This castle has one-hundred floors, reaching almost to the sky. It also has thirty basement floors.
It was later summoned by Kabuto using eight seal tags, to destroy Konoha, as it can absorb people's vitality. The seal tags sealed the castle's memories, so every time they peeled it off, they saw its memories. The vitality that was absorbed within people of Konoha were able to create illusions, with Princess Dusk channelling it. When Konoha 11, Kakashi, Guy, and Gaara came to the castle, which they teamed together to peel of the eight tags, and destroy the castle, while Tsunade, Shizune and Jiraiya teamed to destroy the cauldron from the basement floors, and defeating Orochimaru, thus destroying the castle.
After its destruction, Naruto, Sakura, and Kakashi searched where the castle once stood. In their research, it was said to be somewhere near Konoha. It was also mentioned that Konoha and Castle Dusk were once allied.