Walking this road, without you... To remake forgotten promises and meet you at roads end: Like Sora, Riku traveled through Castle Oblivion, but instead he must fight his way to the top of the basement floors. Though he had been freed from the darkness, it still lingers within him. Now Riku must find a way to defeat this darkness, Ansem, once and for all.

Throughout his journey he finally reaches Destiny Islands. Riku smiles in hopes of meeting his friends, but instead everything is slipping away. Riku continues searching the islands and finally finds Kairi, but she disappears like the rest. Riku breaks down in confusion and Zexion, No. 6 of the Organization appears to him again. Zexion tells him he was the one who threw away everything; his islands, his friends... Soon Sora appears in front of him and swings the Keyblade at Riku. Riku tries to tell Sora it's him, but Sora just scowls and tells him off by attacking him again.

Riku: "I'm...fading... Consumed by the light..."
Kairi: "You won't fade. You can't fade. No power can defeat you — not the light, not the dark. So don't run from the light — and don't fear the darkness. Both will make you stronger."

A light engulfs Riku and he sees Kairi. She tells him that he won't fade. The darkness is his power too. Riku accepts this and calls onto his dark side and awakens. The vision of Sora soon fades to reveal Zexion as the imposter. Riku strikes him but Zexion gets away leaving Riku to travel his way to the top once more.

After traveling and reminiscing through his dark past, Riku finally reaches Twilight Town. Unlike the other places, he doesn't ever remember coming here. A small confrontation with Ansem happens again, and soon enough DiZ was the one disguised as him. DiZ tells him to meet a girl named Naminé then choose, darkness or light? Soon after DiZ disappears leaving a confused Riku.

He travels around the town wondering where to find her but instead finds his double once more. The two fight once and for all leaving the real Riku victorious. Riku travels on and finally comes across a room. There he sees Naminé watching over Sora and his friends.

Riku: "You're Naminé?"
Naminé: "Yes."
Riku: "So...that was you."
Naminé: "Huh?"
Riku: "Nothing, never mind."

Naminé continues on and shows Riku, Sora. Riku is surprised to see his best friend there in the flower like contraption and asks Naminé to tell him everything. She explains the whole truth about his memories and what she did. Naminé tells him that Sora made a decision to keep his old memories and now Riku must choose too. She tells his that she can lock away the darkness and memories of it for good, but he tells her no. He'll make his darkness show him the way.

Naminé: "But if the darkness he wields gets the better of you..."
Riku: "I'll make that darkness show me the way."
Naminé: "That's true."
Riku: "Why do I get the feeling you knew I'd say that?"
Naminé: "I didn't know. I hoped. I want you to face the darkness, because you're the one who can."
Riku: "So that's why you came to me in the light. As Kairi."
Naminé: "You knew?!"
Riku: "I knew as soon as I met you. Somehow you...smell the same. Look after Sora."

Riku soon walks away leaving it up to Naminé to take care of Sora and goes to the last floor to fight Ansem for the last time.