This is addtional content that enables the following songs:

Hitotsuyogari no Touhikou
Scream out!
Against, Perfect Cherry Blossom
SAMURAI GHOST GIRL, KILL! KILL!
far away
Shinreibyou Akimatsuri!
Shoutoku Densetsu ~ True Administrator
Never Come Undone
King of the Sekkyou
Rainy, rainy days
LOVE EAST
Youyoubakko ~ Who done it!
Pandora
Mami Mami Zone
Painting The Lips Red
Desire Drive
Can't look away
Amatsukazeyo
Flower Flag
Marisa Stole the Precious Thing
SWEET BLUE ICE
Tiny Little Adiantum
Shout It Out Loud!!!
Utakata, Ai no Mahoroba
Gensokyo Millennium ~ History of the Moon

More details on the official game page of Extra Song Pack 2 ...