Epsilon (stylized as εpsilon) is Blood Stain Child's fifth studio album and first release on Coroner Records/Pony Canyon. It's also the first to feature vocalist Sophia and drummer Gami (after the departure of vocalist Sadew and drummer/founding-member Violator). All compositions—except "Electricity," which is composed by Aki—are by Ryu. This album was pre-sold during A-Kon from June 10 to 12, 2011. And, in this event, nine of the new songs (including the European bonus track, "Royal Sky") were performed. As of June 7, 2011, Pony Canyon released forty-four second samples of each song in the album; a full sample of "Sirius VI" debuted, through Internet radio, on May 26, 2011. Epsilon continues the trance-oriented sound from Mozaiq, featuring a more polished production and incorporating greater influences from electronic music and J-pop. With the addition of female vocalist Sophia, clean vocals (often with robotic effects) have become prominent, alongside Ryo's screams, which have returned as co-lead vocals. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.