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, someone hugs you tightly, it's a girl, she has blue eyes and blonde short hair.

– WELCOME, NEW RESIDENT! I'M RIN! come with me! i'll show you the others. – she says, grabbing your hand