If you visit Nikko, a World Heritage Site, how do you get there? My answer is by taking the Tobu Railway. You can take it from Asakusa terminal in downtown Tokyo. The Tobu train will take you to Tobu-Nikko, a gateway station to the World Heritage Site. If you specifically choose the limited express train, "Spacia", I guarantee you a pleasant journey, as it has gorgeous interior facilities.
Is there any other route to Nikko? Yes, you can take the JR East Nikko line as the second option. The Nikko line train leaves from Utsunomiya, an interchange station with the Tohoku shinkansen and the Tohoku main line. The Nikko line train will take you to JR-Nikko, another gateway station to the World Heritage Site. According to media, this second option has recently become popular among inbound sightseers, as most of them hold a Japan Rail Pass, which can be used without limits on the JR lines all over the country.
JR East might have been flattered by this increase in passengers. On April 1st, 2018, they launched a new sightseeing train, "Iroha," on the Nikko line. Iroha was modified from set Y3 of the EMU 205-600 series. It is a retro train of a brown color. Passengers can relax with high-grade seats. Free Wi-Fi is provided on the train. The interior displays correspond to major foreign languages. To their joy, no additional fee is applied for taking the Iroha train.
Iroha is named after the famous winding road, Iroha-zaka slope, in Nikko City.
Official information about the EMU JR East 205-600 series, "Iroha" (in Japanese):