Go to the very top of the mountain, where the fire located. Then, move one ledge below and position your character just to the left of the bottom of the fire. Jump left and hold the Joystick in that direction. When done correctly, your character will skip and launch into the air. Just as your character is about to descend, a set of four "dashes" will appear in the following pattern:

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Land on the dash, then jump up to reach a higher ladder. Hold on to the ladder to reach the secret room. Note: The game may crash while your character is in this location.