This is addtional content that enables the following songs:

Mishaguji Empire
Lezamari demo tsurakunai!!
Akutagawa Ryuunosuke no Kappa
Kyouen
Charisma Rengoku Tenshin
Getsurei 11.3 no Candle Magic
GAME OVER (In Disarray)
Romantic Fall feat. Ayakura Mei
Ilias
Shunkan Photography
Non-Stop Ringing Heartbeats
Fabulous
flanticnight
supernatural
Hopeless Discord
Iconoclasm
Marionette Metropolis
Lotus Love
Tenshi no Udedameshi
Hakurei Jinja Chounaikai Ondo
Kanbu de Tomatte Sugu Tokeru ~Kyouki no Udongein
sparkle light
HAZARD AREA
VOLUPTÉ (Game Edit)
Dancing Dollz feat. cold kiss
Hoshi wo Mawase Tsuki yori Hayaku
Septette for a Dead Princess

More details on the official game page of Extra Song Pack 4 ...