Japanese citizens can vote at 18 years of age, but are not considered adults until they reach 20. The voting age was reduced from 20 to 18 in 2016.
 Refers to the Costco Wholesale retail shop in Iruma, Japan.
 Gosetsu (五節) are a set of five festivals celebrated in Japan.
 Referring to the Kameya Eisen sweets shop. http://aboutfoodinjapan.weblogs.jp/blog/2016/04/history-with-sweet-potato-kameya-eisen-sweets-maker-kawagoe.html
 Echigoya is an oft-used name in period dramas for corrupt merchants who bribe officials to get what they want. http://kyouki.hatenablog.com/entry/2014/08/31/212641