Hello, some project diva tracks require these four songs to be activated after passing any difficulty. After the activated songs are passed at any difficulty, other songs will be activated. If you find that it cannot be activated, It means you have to pass all the difficulties. Some of them need to be purchased and downloaded by yourself.

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Hatsune Miku ( Hatsune Miku / Hatsune Miku) is a sound source developed by Crypton Future Media on August 31, 2007 based on Yamaha's Vocaloid series of speech synthesis programs. Library, audio source data sampled from Japanese voice actor Fujita Saki. On April 30, 2010, "Hatsune Miku Append" with 6 different tones of Hatsune Miku was released. On August 31, 2013, the English version of Hatsune Miku was released together with VOCALOID3. In addition, Hatsune Miku also serves as the singer and chorus member of the Japanese music group Sound Horizon.