The introduction of The Adventure of Link speaks of the legend of Zelda, a legend that has been passed down in Hyrule.[3] According to that legend, well before the events of The Legend of Zelda, Hyrule was a prosperous land ruled by a king who had two children, an unnamed prince and Princess Zelda. The King maintained peace in Hyrule using the Triforce; however, he passed away, and although the prince should have received the Triforce in full, he only received a part of it.[4] The prince frantically searched in vain everywhere for the remaining piece, but then a wizard came to the Prince and tells him that his younger sister, Zelda, knows the location of the mystical object.[5] The prince demands that Zelda turn the information over to him, but Zelda refuses and, in a rage, the wizard puts Zelda into an eternal sleep, with him dying in the process.[6] Overcome with grief, the prince seals his sleeping sister in the North Palace and orders that all female descendants of the Hylian monarchy are to be named Zelda.
To break the curse, a hero must possess the complete Triforce, but obtaining the Triforce of Courage would prove difficult as the king of ages ago had hidden it within the Great Palace.[7][8] Only one who proved themselves worthy would obtain it.
In the end, Link obtains the Triforce of Courage from the Great Palace and awakes the sleeping princess from her slumber.
Although both games feature the same Link, this Zelda is different from the one in the original The Legend of Zelda.[9]
The following section is not part of the Zelda canon and should not be taken as such.
In the manga adaption of The Adventure of Link by Yuu Mishouzaki, she is referred to as the First Zelda. Unlike the game, she is not under a sleeping spell, but appears as a phantom.
The First Zelda's phantom appears to Link and the current Princess Zelda, explaining to them that she sealed away Ganon's true self in the Great Palace along with her body using two pieces of the Triforce, and that the Ganon defeated three years ago in The Legend of Zelda was merely one piece of his self. She then sends them on a quest to return the Crystals to the Palaces.
↑Link, the time has come when I must tell you the legend of Zelda handed down in Hyrule. (The Adventure of Link manual, pg. 6)
↑It is said that a long ago, when Hyrule was one country, a great ruler maintained the peace in Hyrule using the Triforce. However, the king too was a child of man and he died. (The Adventure of Link manual, pg. 6)
↑Then, the prince of the kingdom should have become king and inherited everything, but he could inherit the Triforce only in part. The Prince searched everywhere for the missing parts, but could not find them. Then, a magician close to the king brought him some unexpected news. Before he died, the king had said something about the Triforce to only the younger sister of the prince, Princess Zelda. (The Adventure of Link manual, pg. 6, 7)
↑The prince immediately questioned the princess, but she wouldn't tell him anything. After the prince, the magician threatened to put the princess into an eternal sleep if she did not talk, but even still, she said nothing. In his anger, the magician tried to cast a magic spell on the princess. The surprised prince tried to stop him, but the magician fought off the prince and went on chanting the spell. Then, when the spell was finally cast, Princess Zelda fell on that spot and enter a sleep from which she might never awake. At the same time, the magician also fell down and breathe his last. (The Adventure of Link manual, pg. 7, 8)
↑There are three kinds of Triforce -- Power, Wisdom, and Courage. [...] Of the three, I have left Power and Wisdom in the kingdom. But the Triforce Courage I have hidden for a reason. [...] The Triforce of Courage is hidden in the Great Palace in the Valley of Death on the largest island in Hyrule. (The Adventure of Link manual, pg. 9, 10)
↑The magic spell cast upon Princess Zelda will sure to be broken if the Triforce is used. Please, Link. Unite the Triforce and save the princess. And bring back peace to Hyrule. (The Adventure of Link manual, pg. 12)