Given what comes out on the eShop every week, we admit it's hard to believe that Nintendo has guidelines beyond "no Adults Only".
http://www.nintendoworldreport.com/news/69431/idea-factory-cancels-four-localizations-citing-contents-not-complying-with-the-nintendo-guidelines
There were three releases that dropped off the face of the Earth in May, and according to their publisher it's a permanent drop.
Idea Factory International has announced that planned localizations of the Hyperdimension Neptunia Rebirth trilogy of games, as well as the localization of Death End re;Quest: Code Z planned for 2025, have been cancelled. According to IFI's statement, "The 3 Neptunia titles and Death end re;Quest: Code Z for North America and Europe will no longer launch on the Nintendo Switch/Nintendo eShop due to the contents of the Re;Birth series and Death end re;Quest: Code Z not complying with the Nintendo Guidelines".
The Neptunia games previously released on the PlayStation Vita with T ratings from the ESRB, and planned PlayStation 4 and 5 releases for Death End are going ahead.