Hatsune Miku Personalised Birthday Card. "Hatsune Miku", a software program developed by Crypton Future Media, INC. that allows anyone to create a song by entering lyrics and a melody. It became a movement when a large number of creators composed music with Hatsune Miku and posted it on the Internet. As a "character," Hatsune Miku has also gathered attention, and as a virtual singer she is now active in many fields, like merchandising or live performances, and her popularity has spread worldwide. This birthday card has plenty of space on the inside for your birthday wishes too and you can personalise your own inside message.