Simplify the following text for a Grade 6 native English-speaking person.
Original: Refusing to accept defeat , Xemnas separates Sora and Riku from the others to face them in a final battle that ends with his demise . Though initially trapped in Xemnas ' realm , Sora and Riku are able to return to their world after reading a letter from Kairi that reveals the door to light .
Simplified: Near the end of the game , Sora , Kairi and Riku reunite and destroy Xemnas .