The vocals of some of the songs feature Vocaloids.

Hatsune Miku - "COSMO" and "It's A Wonderful World"
Megurine Luka - "Code 03", "Dragon Warrior", "Endless Journey", "Her Sword" and "LNS OP"
GUMI - "COMA" (composed by Vocaloid producer, ensou)
Contributed by DrakeVagabond