The Cursed Swordsman is a character from Twilight Princess. While exploring the area around Hyrule Castle, Link will discover a graveyard behind the castle. When using his senses as Wolf Link, at first Link will see three of the Cursed Swordsman are visible.
The tablet in the back of the Graveyard states that the Cursed Swordsman sleeps beneath the sacred tree. When examining the area as Wolf Link, Link will find a number of the cursed swordsman ghosts surrounding the area just around one of the large trees. Here there is a boulder in the ground that can be blown up with a bomb, revealing a floor switch. Stepping on it opens a nearby gate that has some Lantern Oil, as well as three treasure chests containing 1 Rupee, 20 Rupees, and 100 Rupees, respectively. There is also a torch here, which when lit, causes the rain to stop, allowing Link to light two torches on the other side of the map. This allows Link to reach two statues with the Dominion Rod, which he can then position to jump across and reach a treasure chest containing an optional Small Key.
The Cursed Swordsman later appears near the top of Hyrule Castle in the room with the false floors that will crumble. There are a number of Cursed Swordsman and they point in the direction that Link can safely navigate so that the grown below does not collapse.