Japari bun is now available on Japanese convenience stores (FamilyMart and Circle K Sunkus).
The pink one is chocolate and rum flavor, and the yellow one is cheese and curry flavor.

http://www.family.co.jp/campaign/spot/2018ffesta/japariman.html

Serval's costume seems to be based on the winter costume from Kemono Friends Alarm.

http://kemono-friendsch.com/archives/47196

Also, Ezo red fox throwing the baozi machine is a reference to episode 2 of the manga.