Is this specific EastESIM plan for Japan also valid for travel in neighboring countries such as South Korea or Taiwan?

This particular EastESIM plan is exclusively valid for use within Japan. We understand that many travelers to Asia often combine destinations, perhaps visiting Tokyo before heading to Seoul, South Korea, or Taipei, Taiwan. For these types of multi-country journeys, EastESIM offers convenient regional Asia plans that provide seamless data coverage across several countries. This means you won't need to purchase separate eSIMs for each leg of your trip, ensuring you stay connected whether you're exploring Kyoto's temples or Busan's beaches.