German regulations are the cause of a restriction that reserves mature rated Wii U eShop purchases to the hours between 11pm and 3am, Nintendo has claimed.
In a statement sent to CVG Nintendo of Europe said it is bound to abide by the regulations as it is based in Germany.
"At Nintendo we always aim to provide a safe gaming experience for fans of all ages and ensure that we comply with applicable legal age restriction requirements across Europe," a spokesperson said.
"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.
"Therefore the accessibility of 18+ content in Nintendo eShop is limited to [USK: 22:00 UTC until 4:00 UTC] [PEGI: 23:00 UTC until 3:00 UTC]."
The restriction was discovered last week, when a Nintendo of Italy customer support representative said the company restricts the access to "content which is unsuitable to minors to the 11pm - 3am time window."