This is how Earth-Land has been taken over by Darkness in Kingdom Hearts X (Chi) Back Cover.
Happy: After me and my friends find out about the rumour, and that day before our Journey begins... Darkness has arrived.
Happy is sleeping, and wake up and wake up and find nobody's here
Happy: Natsu? Lucy? Carla? Erza? Gray? Lily? Makarov? Romeo? Where are you guys? I wonder where they went?
He went outside and he look shock, because he saw a Giant Ball above
Happy: Huh? What is that!?
Then he saw Shadow from his Dream
Happy: Not again!
He went off to find his friends and he saw them
Happy: Guys! There you are! What's going on?
Lucy: We don't knwo, and we do know that there is Trouble around Earth-Land!
Gray: And we thought, Zerah is responsible.
Happy: But where is everybody?
Lucy: We don't know, my landlady is not here.
Wendy: Ichiya, isn't here.
Gray: Lyon and the other is not here.
Galjeel: The Sabertooth, is not here too.
Eris: And even though, everyone is gone.
Happy: Where are the guild member?
Levy: I don't know, where they is. But we have trouble from them.
They saw the Shadow
Panther Lily: Greay. Let's fight!
They are fighting them with their Magic and then there are too many of them, and they surrounded them
Juvia: We're surrounded!
Natsu: No fair!
And then the Shadow is gonna tackled them
He hold her to protect her from the Creatures
Then a bright light has save them, and then Natsu and his friends has a Sword
Happy: What happen? And Whoa! Did I have my own Sword!?
Natsu: So am I!
Lucy: Even us!
Erza: But these sword are different.
Galjeet: But how did we get one?
Erza: I don't know, but we have to go find our Friends.
They went off and they saw Mavis
Mavis: Fairy Tail?
Then a burst of Darkness has blown our Heroes away, and they landed on a floating mountain and they saw everything collapsing
Panther Lily: What happen to Earth-Land!?
Then a Huge Shadow has appeared, they are fighting them and they defeated it and then Happy and Natsu has gone Unconscious
Then the huge Shadow has been suck into the Giant Black Ball, and then Happy and Natsu has been drifting away, Lucy, Grey, Carla and Pantherlily are gonna save them and they did it, and now our Heroes has been sucked into the Giant Black Ball