Huh? *tilts head to the side* There is such a thing? 
Free Step Dodge
Uberprinny
Kasumi-Phase-X
Special Day are events exclusive for the demon girls like Nyotengu (Tengu) & Kanna (Oni/Ogre), which are just like birthdays for normal human girls. Since these demon girls don't do birthdays, but get their chances on having special days like humans.