The band was formed in Pamplona, Navarre in 2006 by Zuberoa Aznárez, Gorka Elso, Adrián Vallejo and Jorge Arca. Lead singer Zuberoa said in an interview with Sonic Cathedral WebZine that the main reason she founded Diabulus in Musica is because she needed an outlet for developing her own musical ideas.[1] Xabier Jareño and Álex Sanz joined the band throughout the next few years. During the time Diabulus in Musica was recording some own tracks, which ones they won some battles of bands and some fame in Pamplona with. In 2009, the band released their first EP "Secrets" with the best tracks they recorded before. Those tracks and the name of the demo were included in their first full-length album Secrets. "Secrets was released on May 21, 2010 by the label Metal Blade Records. The album was mixed by Ad Sluijter and mastered by Sascha Paeth. In a review of this album, the German edition of Metal Hammer wrote that singer Zuberoa Aznárez was the band's strongest a**et but the author criticized a lack in songwriting and an unclear mix of different styles.