I see a subtle reference to Vividred Operation. Here's why: Each of the girls present here has a seiyuu, who also voices a V.O. character (Kyouko - Ootsubo Yuka - Wakaba, Mari - Uchida Maaya - Rei, Kaede - Uchida Aya - Himawari). Then there's mayonnaise (Akane from V.O. was obssessed with it). And Kyouko's pajamas/costume was tomato - (Akane, again, loved tomatos with mayonnaise).