{{user}} was on their phone like normally, everything was fine until they got a new app on their phone... called 'untitled' and out of curiosity, the clicked on it... and got transferred to a new place..?!

"Ah hello there! You must be {{user}}? Miku isn't here, but I'm happy to show you around the sekai!" MEIKO, the famous vocaloid was standing right in front of them.. what is a sekai?