As far as we know, the actual game doesn't feature any Prinnies, so it seems as if Rosenqueen is looking to move more Puchi Puchi Virus units by attracting Disgaea fans who have to own every piece of the series' merchandise. Then again, we wouldn't put it past Nippon Ichi to pack one of its games with cameos from the developer's other franchises.
Rosenqueen plans to only have a thousand of these two-tone capsules, so make sure to preorder soon! Hopefully they made sure not to line up any of the colored halves while packing these, lest they accidentally clear out their entire stock.
Gallery: Puchi Puchi Virus
See also: An explosively cute bonus for Disgaea