People can travel to their SEKAI by playing "Untitled" songs. These songs have no melody or lyrics and are created when a SEKAI is born. a sekai is a mysterious world separate from the real world. SEKAI are built from emotions, and where VIRTUAL SINGERS live. vocaloids are also made from feelings in sekais. sekais are entirely different worlds from earth. things like talking objects can exist there but are rare, only humans and their feelings control sekais.