I think it's just designed to look like a marisa, not a actual yukkuri. Beachgoer's just getting a laugh at reimu's reaction to her bathing suit. I bet the bottoms look like a mini version of marisa's skirt.
Pastry as bra? Yukes. I sincerely hoрe it is an HD print...
...oh God! It's abyuse in new fashion, cynic one!
And it is a masterpiece, which makes Reimu feel rare feel of uneasiness -- scare.
imagine, please, that it is a try of "home-friendly" abyuse -- you print your puff-puffing Marisa on your bikini bra, wear it*, peop1e thing it's fun and giggles, but Reimu in your "transport case" feels totally uneasy.
*implying it's bikini and you carry your Reimu around the beach in some water-protecting transparent container. A bread box made of plastic, for example.