Power of waking

The power of waking (眠りし心を解放する力, Nemurishi Kokoro wo Kaihō-suru Chikara, lit. "Power to free a sleeping heart") is an ability introduced in Kingdom Hearts 3D: Dream Drop Distance and plays a key plot element in Kingdom Hearts III, described by Yen Sid as "the power to free a heart from its sleep".

Story

Kingdom Hearts 3D: Dream Drop Distance

Sora and Riku take a Mark of Mastery exam to not only be named Keyblade Masters, but also obtain the power of waking by awakening the Sleeping Worlds. However, Sora loses this power when Xehanort corrupts his heart with darkness. After passing the exam and defeating Xehanort, Riku uses the power of waking to dive into Sora's heart; there, he defeats the Armored Ventus Nightmare and awakens Sora by answering three questions in a vision of the Destiny Islands.

Kingdom Hearts III

"What do you think the power of waking is? It's for traversing hearts to reach worlds. Not for traversing worlds to reach hearts. There's a high price to pay for wielding such power foolishly."

—Young Xehanort, to Sora

Sora travels through the worlds in an attempt to regain the power of waking. Upon facing Vanitas at The Land of Departure, Sora realizes with Ventus's help that the power of waking is still sleeping within him. He then uses the power of waking to free Ventus's heart from within his own and awaken him from his eleven-year coma.

After rebuilding his body in The Final World, Sora uses the power of waking to save his friends from the Lich, traveling between worlds and tracking their hearts down. Young Xehanort reveals that Sora has just used the power incorrectly and put himself in peril for it.

Having tracked his friends' hearts, Sora uses the power of waking to send them back in time to their arrival at the Keyblade Graveyard. Their defeat by the Demon Tower is undone, and the Lingering Will's interference prevents history from repeating.

After the final battle with Xehanort, Sora uses the power of waking to search for Kairi's heart and bring her back. At the Final World, Chirithy explains that the power of waking is only meant to awaken and restore sleeping hearts; by using it to restore hearts erased from existence, Sora has changed history. In spite of Chirithy's warnings, Sora travels back in time to before his arrival at Scala ad Caelum and saves Kairi. In the end, Sora's reckless misuse of the power of waking causes him to vanish into another world.

When Sora used the power of waking to save his friends from Terra-Xehanort's fatal assault at the Keyblade Graveyard, the impact of forcing his friends' hearts back the way they were rewrote reality. This created a singularity, a tear in the fabric of time. The rewrite caused the first version of the battle in which they perished to have never happened. This allowed Sora to relive the battle a second time, where events took a more favorable turn for them.

Kingdom Hearts Melody of Memory

On the search for Sora after he disappeared, the Fairy Godmother takes Riku and Kairi to the Final World, where they meet the Nameless Star. The Nameless Star opens a Portal to the world of Quadratum, and Riku uses the power of waking to travel through it.