Japanese eShop cards are and will only work on a Nintendo Account set to the Japan region.
Since you cannot buy these cards directly from the international Nintendo Store, you must use reputable third-party retailers that offer digital delivery. how to buy japanese eshop cards
: Often the cheapest option because you pay face value without a reseller markup. However, it requires a Japanese billing address (a hotel address often works) and can occasionally block digital purchases on new accounts. Japanese eShop cards are and will only work
