Introduced by Japan's National Confectionery Industry Association in 1978, White Day is celebrated in East Asia on March 14th when recipients of Valentine's Days gifts (traditionally males) reciprocate the gesture with presents for their romantic partners. The Madoka Magica game has presented a series of card featuring the girls receiving their gifts.
Speaking of special designs, there are also new idol cards...
And Mami gets her special kimono design, initially featured on cookie packaging.
This follows the kimono versions of Madoka and Homura