Naruto is only available on specific Netflix libraries due to licensing and copyright agreements. Basically, Netflix doesn’t own this series, so it has to buy licensing rights for specific countries to be able to legally stream the anime there. So Netflix might have the right to show Naruto in the US and Canada, but it can’t do that in some countries in Europe and Asia.
But a good VPN will allow you to connect to a server in your country when you travel abroad to access this anime title in other countries. I recommend ExpressVPN because it always works with Naruto on Netflix, has lightning-fast HD and 4K streaming speeds, and comes with 3,000+ servers in 90+ countries.