Content rated PEGI 18+ only accessible in the European eShop from 11pm - 3am due to German Regulations.
Nintendo responded to Eurogamer's inquiries regarding the restrictions, "Legal age restriction requirements vary across a number of European countries. Since Nintendo of Europe is based in Germany, Nintendo eShop is complying with German youth protection regulation which therefore applies to all our European markets. Under German law, content rated 18+ must be made available only at night."
Attempts to buy or view media related to PEGI 18+ on the eShop in Europe during the prohibited time are met with a disquieting "You cannot view this content." message.