Hatsune Miku is a character in VOCALOID and made appearances in Fanfics.
Acachella ROLEPLAY! Edit
She has a minor appearance in Acachella ROLEPLAY! She has created a mini side quest for Batman to help reunite her with her friends. It is unknown on how she got in the story. A possible theory is that there was a computer malfunction causing the Vocaloid characters to come out of the computer and into the story. She may be later seen in the story perhaps when Batman completes his original task.