Kite had stolen the Emperor's Key.
When Kite manages to go inside the Emperor's Key, he finds Astral, who is visible to Kite inside the key. Astral and Kite exchanges information on why the they are collecting "Numbers", and the two engaged in a Duel.
Believing he will lose, Astral gives up and told Yuma goodbye in his thoughts, even shedding tear. When Yuma manages to recover his Key, it takes him to "The Door" again, the door then opens again and tells Yuma to use ZEXAL
Yuma crosses the door, landing in the dimension inside the Key. Astral and Yuma receive the ZEXAL power, fusing themselves in the process. Using this new power, Astral and Yuma created a card that allowed "Utopia Ray" to defeat "Galaxy-Eyes". Kite managed to end the Duel in a draw and escaped again.
Is this clear enough??