Simplify the following text for a Grade 5 native English-speaking person.
Original: The three arrive at the headquarters of Organization XIII , with Kingdom Hearts looming overhead , and Sora is finally reunited with Kairi and Riku after defeating all of the remaining Organization members , save Xemnas . Roxas is also revealed as Sora 's Nobody , whom Riku had captured by willingly assuming the false Ansem 's form , in order that Roxas may be integrated back into Sora .
Simplified: Sora rescues Kairi and Riku and defeats Ansem .