Riku's story begins a number of years before the night of the heartless invasion of Destiny Islands. Years before the heartless attack, there was a meteor shower, and when it finished, a mysterious girl appeared on the Island. Her named was Kairi, and she is from another, far off world (although she is unaware about her exact origin) and is now stuck on the Island. Soon after Kairi's arrival Riku and Sora go to their secret place, a small cave that they explored. Sora is fascinated by it, but soon decides to leave. Riku however, catches sight of an enigmatic door. From this day on, Riku became obsessed with finding what lies beyond the door, hoping it to be a pathway to another world (such as Kairi's).
As Kingdom Hearts begins, Riku is a cool and collected 15 year old who lives with his best friends Sora and Kairi on Destiny Islands. The three spend their time constructing a raft and gathering supplies, hoping that they might one day set out and search for other worlds. Sora and Riku have always had a friendly rivalry, competing in random battles that range from sword battles (using wooden swords) to running races, often these competitions are to win the attention and affection of Kairi.
The night before the three are to embark on their journey to find other worlds, Riku finally manages to open the mysterious, enigmatic door in Sora's and his secret palce, only for the Heartless (beings of darkness without hearts) to emerge and invade Destiny Islands, seeking the World's heart. Both Kairi and Sora would set out to find the raft to protect it. Sora soon comes accross Riku, who is obsessed with finally escaping the island. Mysterious darkness surrounds the two, and Riku embraces it, while Sora opposes it. Subsequently, Riku disappears into the darkness while Sora breaks out of it, and gains the Keyblade
Riku ends up in Hollow Bastion (the Heartless' headquarters), seperated from his friends. He is then found by Maleficent, who proceeds to manipulate him into thinking Sora has forgot about him, telling him that the only way to save Kairi (who lost her heart to the darkness) is to ally himself with her, abandoning Sora in the process. Riku doesn't believe Maleficent, and meets up with Sora, but that ends up making him believe in Maleficent's idea's, unlike before. Upon leaving Sora, he finally agrees to side with Maleficent, although he remains suspicious of her.
Maleficent eventually grants Riku the power to control all the heartless, a power he shows off in Neverland when he creates a heartless version of Sora to fight. Riku also reveals that Kairi's body is in his possession, although she is completely unconscious as she is without a heart. Riku grabs Kairi while Sora is fighting his heartless and recklessly returns to Malificent's castle via the Corridors of Darkness without a vessel, which exhausts even Riku's powerful heart. While he is drained, Malificent unlocks the last of Riku's power and plunges Riku in darkness.
Sora finds his way to Hollow Bastion and is confronted by Riku, who coldly reveals that he is the true keyblade master, and that Sora is only the "Delivery Boy". Riku then uses his new powers unlocked by Maleficent to take control of the Keyblade, giving Sora a wooden sword as a replacement. Riku leaves, and Goofy and Donald reluctantly follow him (as their orders were to follow the Keyblade master). Despite being significantly weakened, Sora makes his way to the foyer of the castle to confront Riku again. Riku, now with a new, dark appearance after seemingly being consumed by darkness, tells Sora to quit, but Sora refuses to leave without Kairi. Riku intends to prove that he is the stronger of the two, attacks Sora only for Donald and Goofy to come to Sora's aid. Sora realises that he doesn't need a Keyblade, and that as long as he has his friends by his side he can go on without it. Upon Sora's epiphany, he regains the Keyblade from Riku, becoming the Keyblade master yet again. He then forces Riku to retreat deeper into the castle.
Upon his retreat, Riku is puzzled over why the Keyblade went back to Sora. A mysterious voice talks to him from the Darkness, and tells him that only the one with the strongest heart may wield the Keyblade and that Riku was weaker then Sora. This mysterious voice beings to take shape, and offers Riku a Keyblade of his own, although this Keyblade was special in that it had the power to unlock the darkness in peoples hearts. However, Riku must bcome one with Darkness in order to wield it, and misguided by his urge to own a Keyblade and be the stronger of the two, Riku agrees.
Riku then becomes possessed by this mysterious being, and this new Riku then presents himself to Maleficent, warning her of the dangers of unlocking the Final Keyhole (to Kingdom Hearts itself). She tells him not to be afraid, and goes off to deal with Sora. After Maleficent is defeated, Riku appears with his Keyblade and pierces Maleficent's chest, unlocking her heart, allowing the immense darkness that is attracted to her to overtake her heart, transforming her into a giant dragon. Riku then retreats, leaving Sora to deal with this new form of Maleficent.
Riku begins calling himself Ansem, Seeker of Darkness (as Ansem has now posessed Riku) and later confronts Sora yet again before the Final Keyhole. He hopes to release Kairi's heart from within Sora's so that she, being the final Princess of Heart, can open the Keyhole. He once again fails to defeat Sora, but Sora impales himself regardless to save Kairi. With Sora gone, Ansem attacks Kairi, Donald and Goofy, who are saved when Riku uses his last ounce of strength to hold the dark powers of his possessor off. Riku's rejection of Ansem leads to an internal struggle between the two, which Riku loses, causing his to lose control of his body once more, while Ansem gains full access to it.
After Kairi had hugged Sora's heartless, causing him to find his light and become Sora again, he Donald and Goofy made their way to Hollow Bastion, then the End of the World, the home and birthplace of the heartless. They once again confront Ansem and defeat him after a series of battles at the Door to Darkness. Ansem is defeated when Sora opens the Door to Darkness, causing light to burst out, overwhelming and destroying Ansem. Upon Ansem's defeat, Riku is restored and is found within the Darkness in the Door to Darkness with King Mickey, who help close the door from the inside while Sora, Donald and Goofy close it from the outside, and Riku is stuck inside with the King.
Kingdom Hearts: Chain of Memories
Riku awakes in the lowest basement of Castle Oblivion, being led there by his heart resonating with Sora, who also stumbled into Castle Oblivion, although on the ground floor. A dark card and a disembodied voice present themselves, the voice offering Riku the chance to sleep and forget his troubles as well as the light, or take the card and take the first steps toward the truth. Riku of course chooses the card. He soon arrives in Hollow Bastion, though a version created through his memories. Despite Hollow Bastion being the same as he remembered it, he is unable to find anyone, and is mocked by the mysterious voice as he searches for people. He finally meets Maleficent, who taunts him and his refusal of the darkness. Riku fights and defeats Maleficent, proving that he is above darkness.
Riku then leaves, only to see Castle Oblivion in its truest form. The voice once again comes to Riku, revealing himself to be Ansem, who wishes to take over Riku again. Ansem is powerful, but Riku is aided by King Mickey, and the two fend off Ansem for the time being, although he leaves Riku with World Cards and the ability to wield his inner darkness as a weapon.
Riku soon realizes that he has the power to detect darkness, and is discouraged by it, although Mickey confronts Riku about it (although Mickey can only appear as a projection to Riku as he is still in the Realm of Darkness), and with Mickey's encouragement, Riku ascends the basements of Castle Oblivion hoping to rid himself of the darkness within him. As Riku travels from the basement up, Sora travels from the ground floor up, being manipulated by Marluxia (a member of Organization XIII the the keeper of Castle Oblivion) and getting his memories erased, while three other Organization Members ( Vexen, Lexaeus and Zexion) work to counter Marluxia by using the darkness-wielding Riku against the light-wielding Sora.
To achieve their plans, Vexen independently appears before Riku making Riku think Vexen is with Ansem, which Vexen denies. Still, Riku attacks Vexen, feeling him to be hostile, which only helps Vexen, who uses the data he gathered from the battle to create a Riku Replica. The replica soon battles Riku, mocking Riku's fear of the darkness while the replica embraces it. Riku is victorious however, and the replica retreats.
Soon Ansem appears again, saying that the replica is a model that Riku should be, but Riku makes it clear that his desire is to conquer the darkness within him. Passing through much of the castle, Riku finds Lexaeus who tells him to accept the darkness within him, because if he doesn't, his journey will end here. The two battle, and Riku is able to defeat the powerhouse. WIth his last strength, Laxaeus covers the room in darkness as Ansem once again attempts to purge Riku's heart, only for Mickey to save him again and manage to bring him out of the darkness.
As Marluxia's scheme fails and Sora defeats him, Riku senses Marluxia's defeat, and Zexion soon arrives on the scene to explain it. But he also reveals that Sora is the one who defeated him, much to Riku's suprise. Zexion asks if Riku is capable of seeing Sora, as Riku neglected the darkness for so long and Ansem still resides in his heart. Zexion then gives him the World Card to Destiny Islands, and Riku enters.
In Destiny Islands, Riku meets all of his friends, but they are all silent and they eventually disappear, even Kairi. Zexion throws all of Riku's fears at him at once, telling him he's responsible for causing them to disappear, and that he belongs to the darkness now. He finally transforms an illusion of him into a Darkside Heartless, telling him this is what he has become. Riku beats back the Heartless as Zexion disguises himself as Sora. He tells him that it's finally time to face the light.
Riku sinks into the light as he begins fade, but Kairi appears and tells him that he can't. Light can't beat him, neither can darkness, so he should accept both, then he won't be afraid anymore. He awakens his dark power again, admitting that it's a part of him and not evil, beating back Zexion. He disappears, but is quickly killed by the Riku Replica with Axel.
Riku nearly makes it to the main floor as Ansem appears to control him, but King Mickey offers his help again and finally appears in person, pleasing Riku who finally has a real friend with him. Mickey shows Riku a card containing Riku's heart which he used to find Riku. He gives the card to Riku, who uses the card and finds himself in Twilight Town. In Twilight Town, Riku meets a stranger named DiZ, who Riku recognises as the voice he heard when he was at the bottom of the Castle. DiZ tells him he wants Riku to choose between Light and Darkness, because he lies in-between at the moment, and that the decision will be decided with Namine (a character used by Organization XIII to erase and change the memories of Sora), who Riku looks for.
Riku finds Namine who is with Sora in his memory pod, and explains to him the situation. She offers to seal away Ansem and Riku's darkness so that he may forget them, but will have to put him to sleep, similar to Sora, to do so. Riku refuses this offer, hoping to win the internal battle on his own and leaves Namine. Before he leaves however, Riku mentions that he knows it was her that came to him disguised as Kairi.
After their meeting, DiZ appears again to Riku and King Mickey (who notes that DiZ seems familiar). Aware of his choice, DiZ gives Riku a card that will rid him of Ansem, then leaves. After his
departure, Riku asks Mickey to destroy him should he fail to stop Ansem, but he refuses, saying he'll only help him regain control and never harm him. Riku reluctantly agrees, and faces Ansem for one final battle alone. Ansem asks why he still refuses to accept him and the darkness, but Riku merely replies "You just really stink". They fight and Ansem is defeated, although he tells Riku that he is a part of him and he shall return.
Riku and Mickey wait at the front entrance. Riku tells him that he can't go home yet as "Ansem's" shadow still lingers in him, but Mickey says the darkness is a part of him. Darkness is not all bad, because Riku has chosen a road he never thought of before, one of both Light and Darkness. They leave, taking Organization cloaks that DiZ gave them prior to confronting Xehanort's Heartless, and DiZ appears for one final question: if he shall take the "road to light" or the "road to darkness". Riku chooses neither, he'll take the middle road, "The Road to Dawn". Riku and King Mickey eventually made it out of the plains and separate after Riku realized he couldn't completely rid himself of the darkness festering in him. Deciding to return to DiZ and offer his help, Riku dons a blindfold, for "his eyes couldn't lie" about his darkness which he is preparing to use and wished Mickey not to witness firsthand.
Kingdom Hearts II
In Kingdom Hearts II, Riku allies himself with DiZ as they both share the same goal (to help Sora awake from his slumber induced by Namine). However, Riku wants no part of DiZ scheme of revenge, and only wishes to get his friend back, and as a result locates, defeats and kidnaps Roxas (Sora's Nobody) as if Roxas merges with Sora, Sora will re-awaken. Riku enters the Realm of Darkness and finds Roxas is The World that Never Was. Upon beginning their battle, they appear to be evenly matched, until Riku realises that as he is in the Realm of Darkness, he must open his heart to darkness in order to battle to his full capabilities. Riku unleashes his darkness, overwhelming Roxas, although as a result Riku takes the form of the Darkness in his heart - Ansem.
DiZ errases Roxas' memory and he is placed into a virtual Twilight Town created by DiZ, where he lives out the last days of his life until he finally merges with Sora. Riku watches over Roxas during this time, often entering the town in order to keep Roxas unaware of the truth (including stealing their money so they are unable to take a train to the beach, which if they did, would mean DiZ would have to create a virtual Beach, and also keeping Namine from telling Roxas the truth). After Roxas merged with Sora, Riku was ordered to kill Namine, but he instead handed her to the renegade of Oranization XIII - Axel.
After Roxas becomes one with Sora, Riku then contacts King Mickey, telling him not to reveal his whereabouts and appearance to Sora, and Mickey agrees. He then gives Mickey the virtual items Olette
's money pouch and Roxas' crystal orb (that he stole from them in the Virtual Twilight Town
for different reasons).
Later on in the game, Riku rescues Kairi after Axel kidnaps her in an attempt to turn Sora into a heartless. Riku takes her to Twilight Town (where she meets Roxas' friends Hayner, Olette and Pence), although his identity is never revealed to her. Axel appears again, but Saix (another Organization XIII member) appears, prompting Axel (who is a renegade to the Organization) to flee. However, Saix then kidnaps Kairi, hoping to fuel Sora's rage.
Towards the end of the game, Riku appears in The World that Never Was, coming to Namine and Kairi's rescue (the two were confronted by Saix after Namine rescued Kairi who was being held prisoner). As Riku exits, Namine calls him by name, and Kairi, excited to see Riku after over a year, removes his hood but finds Xeharnort's Heartless (it was revealed earlier in the game that the "Ansem" Sora battled in the original Kingdom Hearts was in fact the Heartless of Ansem's apprentice, whose name was Xeharnort, and that Xehanort's Nobody, Xemnas, is the leader of Organiztion XIII). Despite his new appearance, Kairi see's that it is still Riku underneath and is still overjoyed at finally seeing him again.
Riku once again saves Kairi when she is attacked by the Heartless on her way to seeing Sora and gives Kairi a keyblade so that she can fight them off herself. After Sora defeats Xigbar, he is reunited with Kairi. Riku tries to leave before Sora see's him in his current state, but Kairi stops him, and reveals his identity to Sora. Like Kairi, Sora is also able to see and appreciate Riku under Xeharnort's Heartless' darker appearance, and is, like Kairi, overjoyed to be reuninted with Riku. He, Sora, Kairi, Donald and Goofy then travel up the castle and defeat Saix and Luxord, making Xemnas the only remaining member of Organization XIII.
Near the top, Riku reunites with King Mickey and DiZ, his true name being Ansem the Wise, who is using a machine to try and encode Kingdom Hearts into data. Xemnas also arrives, and he and Ansem the Wise trade bitter words. The machine then explodes, unable to handle Kingdom Hearts, killing Ansem the Wise while causing countless hearts Xemnas had collected into Kingdom Hearts to rain down on the world, reuniting with nobodys. The explosion also restores Riku to his original form, though he is still remorseful. After some encouragement, Riku transcends the rest of the castle, abandoning his cloak and blindfold. He and the others also encounter Maleficent and Pete
, who decide to hold off the hordes of Heartless that are overtaking the castle, but only so that they will eventually take the castle for their own.
Riku and the others then confront Xemnas, refusing his demand to gather more hearts. Xemnas then removes Sora from the area, fighting him one and one, with everyone else calling out to him.
When Sora returns, they see that Xemnas has already reached Kingdom Hearts, and disappears into it. A door, constructed by the will of the worlds, appears, and the three wielders of the Keyblade open it up and follow Xemnas. After a tough battle, Naminé appears again, opening up a corridor of darkness that leads to Destiny Islands, as Riku can no longer use them. However, Xemnas attacks, riding on a gigantic robotic dragon, and separates Sora and Riku from the others. After a series of battles, the two of them are drawn into nothingness by Xemnas and face in a final, exhausting battle. Towards the end after the final attack used by Xemnas, Sora is left open and Riku takes a blow intended to finish off his friend, which allows Sora to finish Xemnas off with both Riku and Sora firing a beam of light from Sora's keyblade. However, after the battle they end up in the Realm of Darkness. Having the time to finally talk, the two reconcile with each other. Riku then comes across a letter in a bottle, written by Kairi, and gives it to Sora, believing him to be the proper recipient. Sora then manages to open the Door to Light, as King Mickey predicted, and the two return home, reuniting with their friends.
Some time later, Sora, Riku, and Kairi receive a letter from the King, however, the contents of the letter remain unknown.
Kingdom Hearts 358/2 Days
Riku appears as an important side character in Kingdom Hearts: 358/2 Days
. In it, he works with Namine and DiZ in their attempt to restore Sora's memory so that he can awaken. He infiltrates Organization XIII and is the first from outside the Organization's ranks to make contact with Xion
, the Sora replica constructed from memories of Kairi. He is eventually successful in convincing Xion to go to Namine.
Shortly thereafter, Xion is recaptured and returned to the Organization, but she escapes again and is eventually defeated by Roxas, allowing the memories she's made of to return to Sora. When Roxas returns to the World That Never Was
in order to destroy Kingdom Hearts, Riku steps in to stop him. Unable to stop him, Riku is forced to unleash the darkness he had trained himself to control, taking on Ansem's appearance in order to subdue Roxas and return to DiZ and Namin
e with him.