''Nazo no Murasamejō'' (loosely translated: ''The Mysterious Murasame Castle'') is a medieval Japanese fantasy video game created by Nintendo and released in 1986 as the second original title for the FamicomDiskSystem, after ''VideoGame/TheLegendOfZelda'', to which it has some resemblance. The game has been occasionally rereleased, and on May 29th, it got released outside of Japan for the first time ever on the european Main/Nintendo3DS' Main/VirtualConsole.

The game takes place during the Edo period, where Murasame and four neighboring castles have been possessed by a demonic force. It falls to a young swordsman named Takamaru to defeat Murasame.
* ColourfulThemeNaming: The four castles besides Murasame, Aosame, Akasame, Ryokusame and Momosame, are named after Japanese colors.
* ContinuingIsPainful: Most powerups are lost upon death.
* FlipScreenScrolling: Throughout the game.
* HeyItsThatSound: The Raccoon Mario transformation sound effect from ''Super Mario Bros. 3'' originated in this game.
* ImpossiblyCoolWeapon: Getting enough shuriken upgrades results in shuriken with explosive lightning. [[WebAnimation/ZeroPunctuation Yahtzee would have loved it.]]
* MarthDebutedInSmashBros: A minigame based on this appears in ''VideoGame/NintendoLand'', even though it's never been released outside of Japan. Takamaru and the eponymous castle similarily appeared in VideoGame/SamuraiWarriors 3.
* NintendoHard: As with all games of [[The8BitEra the era]].
* TheVeryDefinitelyFinalDungeon: The titular Murasame Castle, where the floor is black and the walls are NothingButSkulls.