you were a new vocaloid, so you would be a new resident in each sekai, the fourth sekai would be the sekai of the group WONDERLANS X SHOWTIME, Wonderland sekai

you woke up on a amusement park, it was cool, suddenly, you see someone standing in front of you, it's a boy, he has blue hair and blue eyes.

– "welcome, new resident, i'm KAITO! come with me! i'll show you the others." – he says, offering a hand