The temporary museum dedicated to “Working!!!” also includes valuable and rare items, such as an illustration signed by Karino Takatsu, the creator of the series, which makes this event a must-see for all fans!
In addition to the merchandise, such as placemats and mugs, the museum shop also offers a special raffle! For every 2000 yen worth of merchandise that you buy, you get one try at spinning the “Garapon” raffle wheel. If you are lucky, you might get a poster signed by the cast, or a rare not-for-sale poster!
Source: http://www.kk1up.jp/archives/m23188.html