Uhh, Wakana tagged this as Hatsune Miku. I don't really know what this design is, if it's an original outfit or cosplay or whatever (I also don't know what the "World is Melting" thing is).
Here's what Wakana has to say about it: 和訳: 世界が君にめろめろなのさ 夜明けのテンションで描きあげてしまっていろいろ後悔しています。