Mysterious Tower

Mysterious Tower is a world in Kingdom Hearts II, Kingdom Hearts II Final Mix, Kingdom Hearts Birth by Sleep, Kingdom Hearts Birth by Sleep Final Mix, Kingdom Hearts coded, Kingdom Hearts Re:coded and Kingdom Hearts 3D: Dream Drop Distance. The tower serves as the home of the legendary ex-Keyblade Master, Yen Sid and a repository of great knowledge acumulated by the mighty wizard.

The Symphony of Sorcery originated the Mysterious Tower, before turning into is a sleeping world that appears in Kingdom Hearts 3D: Dream Drop Distance, the second to be based on Disney's 1940 feature film, Fantasia. Also, Like Timeless River and Country of the Musketeers, Symphony of Sorcery is set in the past, during a period where Mickey was in pursuit of knowledge to become a Keyblade Master.

Both serve as starting points for Sora and Mickey's quests in Kingdom Hearts II and Kingdom Hearts Birth by Sleep, respectively. Although it is considered part of Twilight Town in Kingdom Hearts II, like Dive to the Heart and Betwixt and Between, it is its own world and not part of the other.

Development
Since the conception of the first Kingdom Hearts, Tetsuya Nomura had wanted to include a world based on Fantasia, but was unable to and ended up only including Chernabog as a boss in End of the World, though in a battlefield very similar to the Night on Bald Mountain segment.

Outside the Tower
In Kingdom Hearts II, the Tower resides in a secret area of Twilight Town, accessible only by a special train that only appears sometimes in the Central Station. The Countryside itself consists of several hills apparently floating amongst the clouds in the endless sunset of Twilight Town, with several stars gleaming in the background. Other than the hills and the tower itself, the only physical existence in the Countryside is a glowing railway along which the single train rides.

The Tower itself is a surrealistic, crooked, golden-brown tower, loosely based on the setting of Fantasia's The Sorcerer's Apprentice. Though it appears to be missing several key structures from the movie, such as the well and the basement study, it appears that the segment is canon to the Kingdom Hearts storyline, and this tower is where it takes place.

The Tower is topped with blue cone-shaped turret roofs, decorated with moons and stars, similar to Yen Sid's hat. It rests on a floating island that contains a courtyard and many trees that obscure the rest of the Countryside from view.

Inside the Tower
Inside the main door is a simple round room, surrounded by an upward-spiraling staircase that leads to a strange portal. Through the portal, a person is transported to higher areas of the Tower, where the staircases float randomly. They lead into other portals or doors to other parts of the Tower.

Other than the entrance, stairs, and upper floor, there are two known rooms in the Tower. One is the Moon Chamber, and the other is the Star Chamber. Both are perfectly round rooms, each with two doors leading either up or down the Tower, and are decorated with moons and stars, respectively, which glow when Heartless are present. The final stairway is steep and straight, and leads to Yen Sid's Study.

Yen Sid's study is the largest room in the building, with several shelves containing many books, several about the exploits of King Mickey. There is a large wooden desk behind which Yen Sid sits, and behind it, large star and moon windows displaying the Countryside.

A door on the side of the study gives way to the Wardrobe Room where the Three Good Fairies, Flora, Fauna, and Merryweather, apparently stay. There is also a large wardrobe, and several covered mirrors that display Sora in his drive forms, including Anti Form and Final Form.

In Kingdom Hearts Birth by Sleep, the portals to the other rooms make no appearance and the Wardrobe Room is inaccessible.

Kingdom Hearts Birth by Sleep
During Kingdom Hearts Birth by Sleep, Mysterious Tower is first seen at the beginning of the game. Mickey is shown riding a book over waves of water, before being sucked down a whirlpool. Suddenly, the water disappears and Mickey appears in Yen Sid's study. Yen Sid looks disappointed, before saying that he senses that something horrible is about to transpire.

Terra is the first of three Keyblade wielders to visit the tower. After learning that Master Xehanort is in a battlefield wasteland from the Magic Mirror, Terra goes to see the former Keyblade Master, Yen Sid to gain more information. As he arrives, he sees Mickey disappear into a flash of light from his Star Shard.

Terra continues to go see Yen Sid. Yen Sid sensed Terra's arrival and Mickey's departure as he can sense the movements of Keyblade wielders. Yen Sid says he feels that the Unversed and Xehanort may be connected and sends Terra back on his search for Xehanort. As the young man leaves, Yen Sid asks himself if Xehanort still has "distracting thoughts".

Ventus appears here accidentally by Star Shard while visiting Neverland. As he lands, Donald and Goofy are sitting outside wondering where their King has gone. They at first mistake Ven for the king but then take him upstairs to Yen Sid. The old man notes that Eraqus ordered Ven to return home, but says Ven is just like Mickey that way.

Ven says that he does not know where Mickey is, so Yen Sid finds him. He shows Ven, Donald, and Goofy an unconscious Mickey in the Keyblade Graveyard, abducted by Master Xehanort. Donald and Goofy prepare to venture out to save Mickey, but Yen Sid persuades them otherwise, knowing that they are no match for Master Xehanort. In the end, Ven goes alone, to repay his debt to Mickey for saving him earlier.

Aqua comes here after finding Mickey unconscious in the space between worlds. She flies him to Yen Sid, and while Donald and Goofy try to wake him up, Yen Sid tells Aqua of Eraqus' defeat at the hands of Terra. Aqua furiously denies that Terra could do that. Yen Sid hopes this as well, but tells Aqua to find the truth by talking to Terra himself in the Keyblade Graveyard. She leaves with Yen Sid warning her to be careful. After Aqua's showdown with the Vanitas-possessed Ventus, Mickey brings the two to the Mysterious Tower.

However, Ven is unconscious, stuck on the border between light and darkness. Yen Sid tells Aqua that she must believe in her friends to save them. If she treasures the bonds she shares with Ven, he will be led back to light. Mickey agrees to believe in Ven too, and Aqua says Terra will too, when she finds him again. Until then, Aqua departs with Ven to find a safe place for him to sleep.

During the end credits, a dejected looking Mickey, standing beside Donald and Goofy, places his Star Shard and Keyblade on Yen Sid's desk. As he turns away, Yen Sid returns it to him, as the King raises it in pride.

Kingdom Hearts II
After Sora awakens from his year-long sleep in the basement of the Old Mansion, he meets briefly with King Mickey, who gives him munny and tells him to take the mysterious train to Yen Sid. After being seen off by Hayner, Pence, and Olette, the three take the train and arrive at the base of the tower.

Getting off the train, the trio meet Pete, who is loitering outside after sending in Heartless to attack the Tower's master. Due to the tower having changed it's location since the events of Kingdom Hearts Birth by Sleep, Donald and Goofy are unfamiliar with the tower and are startled to hear that Yen Sid resides there. The three hurry inside to meet the King's tutor, leaving a bewildered Pete behind.

They make their way to the top, slaying Heartless on their way up, and eventually reach Yen Sid. The sorcerer gives them a book that summarizes all three games, and gives them information about the Nobodies and Organization XIII. He and the good fairies also give Sora his new outfit and drive form abilities, and returns the lost Gummi Ship to Donald and Goofy.

After the party leaves, Diablo, Maleficent's Raven, arrives with Maleficent's robe that was left in Hollow Bastion. The three good fairies recognize it immediately, and their memories of its owner start to work magic on it and bring Maleficent back to life. She plotted to take over the Tower and announced her return with her trademark laugh.

It appears, though, that she failed, as she instead began targeting other castles all over for the same reason, and later, when the player can return to the Tower, there is no evidence that she ever held any sway over it. However, Yen Sid and the Good Fairies are completely absent, and the Tower is overrun by lesser Nobodies.

Signs of What's Next
Some time after decoding Jiminy's Journal, Mickey returns to the Mysterious Tower to meet with Yen Sid, who appears to have regained control of the Tower from the Nobodies. They discuss the whereabouts of Terra, Aqua and Ven, as well as the next actions of Master Xehanort, who will be revived due to the defeat of Ansem and Xemnas. Yen Sid orders Mickey to summon Sora and Riku to him to undertake a Mark of Mastery Exam to counter Master Xehanort.

Kingdom Hearts 3D: Dream Drop Distance
To counter the return of Master Xehanort, Yen Sid has Sora and Riku brought to him in order to be tested for the Mark of Mastery. He sends them to the Realm of Sleep to unlock the seven Sleeping Keyholes of worlds that did not completely return after Ansem, Seeker of Darkness was defeated; doing so will grant them magic to awaken hearts from their sleep and restore the remanining worlds trapped in dreams. Creature called Dream Eaters, as he explained, will guide them. King Mickey, Donald and Goofy await their return here until Maleficent's raven brings a letter explaining Queen Minnie's capture; Yen Sid belives Maleficent's descion to do this now is too well-timed due to Master Xehanort's eventual return.

Once Queen Minnie is safe thanks to Lea's help, Yen Sid is shocked that the former Nobody wishes to gain a Keyblade of his own. Despite Donald's protests, Yen Sid explains that since a member of Organization XIII is now a complete person again, Master Xehanort will not be any different; they must take any action that will give them an edge over their foe. He then has Merlin and the Three Good Fairies compress the training Lea would need to learn how to weild a Keyblade. As his attempts to locate Sora and Riku end questionablely, Yen Sid begins wondering how far Master Xehanort could have plan things in advance. When Goofy wonders if he could have jumped back in time to when Destiny Islands was consumed by Darkness], they stumble upon the truth: Xehanort had given up his body by becoming a Heartless and had possessed Riku aroud the same time. This would mean Sora and Riku are in grave danger. Able to locate Riku now, Yen Sid sends Mickey to The World That Never Was.

After Sora is rescued thanks to Riku, Mickey, Lea, Donald and Goofy, Yen Sid is told about the Thirteen Seekers of Darkness Master Xehanort plans to pit against Seven Guardians of Light to forge the X-blade. With Sora canatonic due to his heart being damaged by the Organization to make him a suitable vessel for a fragment of Xehanort's heart, Riku, having unlocked seven Sleeping Keyholes in Sora's dreams, dives back into the Realm of Sleep to free Sora's heart from a Nightmare and recover the research data of Ansem the Wise hidden deep within it. With these events doen, Riku is named a Keyblade Master while Lea finally manages to summon his Keyblade.

Sora departs to the sleeping Traverse Town to thank all the Spirits that helped him and Riku during their journey. In the meantime, Lea returns to Radiant Garden while Riku brings Kairi to Yen Sid to be trained to wield her Keyblade; he reasons it's better to have seven Keyblade weilders face Master Xehanort's Organization instead of putting all the Princesses of Heart in danger.

Kingdom Hearts 3D: Dream Drop Distance
Mickey resides in this sleeping world, during his time under Yen Sid's tutelage. Using the magic of his master's hat, Mickey fools around, accidentally summoning the Spellican that escaped from Traverse Town. Using the Sorcerer's Apprentice musical score, the Dream Eater places him in a nightmare while his unconscious body "conducts" the music in an aura of darkness.

Sora arrives within the Sorcerer's Apprentice musical score, watching the dream projection of Mickey use the magic of Yen Sid's hat to the fullest before the Spellican knocks Sora out of the music book and into Yen Sid's chamber. Sora summons his Keyblade to break the spell placed on Mickey, and fails. Mickey telepathically contacts him, wondering who he's an apprentice to because of his Keyblade. After Sora stops himself from addressing Mickey as Your Majesty and realizing where he is, Mickey informs Sora that they need a "Sound Idea" to break the Spellican's hold on him. A new musical score is conjured by Mickey; the Sound Idea lies within. Using his Keyblade, Sora enters the musical realm of the Pastoral Symphony and finds the Sound Idea.

However, he once more meets Young Xehanort, who leaves him with cryptic clues before leaving. Sora returns to Mickey and tries conducting the Sound Idea, but finds it ineffective. However, Sora has hope that Riku will pick up the slack; a second Sound Idea appears and both merge. The resulting music is "Dearly Beloved". Mickey is amazed that the two Sound Ideas merged as the way to the Spellican opens. Sora enters the new musical realm and defeats the Dream Eaters, rescuing Mickey. Back from his dream, Mickey thanks Sora, but then rushes off to fetch water to avoid getting in trouble with Master Yen Sid. Sora unlocks the Keyhole.

Riku arrives in the Tower Entrance, finding water rushing down the stairs; Mickey had brought the brooms to life to fetch water in his place, leading to this. Finding Mickey in the same predicament as Sora had, Riku prepares to bash the sheets of music to free his friend from their spell. However, Mickey telepathically informs Riku they need a Sound Idea to break the hold of the darkness that music is eminating from. Being given a new sheet of music to use as an entrance to a musical realm, Riku enters the Nutcracker Suite, finding his Sound Idea. However, no sooner has he done so than he is transported to Bald Mountain, where Young Xehanort appears before him. The enigmatic being reveals that Riku is of no more use to "them" and that his abyss awaits. Chernabog arrives from the flames of Bald Mountain and is defeated by Riku.

Riku returns and uses the Sound Idea on the possessed sheets of music. Mickey is left to wonder if one Sound Idea is not enough, but Riku confidently tells Mickey that he has a friend that can help. Sora's Sound Idea appears and merges with Riku's, producing the same music as before. Mickey is now freed from the spell of the Darkness, thanking Riku. Riku mentions Sora's name, saying it's hard not to smile around him. Mickey then hopes he can join Riku and Sora's team some day. Riku laughs, knowing that Mickey will, saying that he can. Riku unlocks the Keyhole.

Trivia

 * Strangely, the Unversed never infiltrate Yen Sid's home. However, in Kingdom Hearts II, the path to his chamber becomes harder to reach due to random portals leading to another dimension full of stairs. This indicates it's a fail-safe defense mechanism Yen Sid has to repel intruders, given Nobodies infest all but the top floor of the tower after Yen Sid and the fairies leave it and the portals remain.
 * Again, in Dream Drop Distance Dream Eaters never enter the Tower and only infest the garden outside and the musical scores.