Is this CoreESIM plan valid for neighboring countries such as Japan, South Korea, or Hong Kong?

This specific CoreESIM plan is exclusively provisioned for use within Taiwan. Its geographic scope does not extend to other Asian nations. Should your itinerary include onward travel to destinations like Tokyo, Seoul, or Hong Kong, your data service will terminate upon exiting Taiwan. For multi-country journeys across Asia, CoreESIM recommends its dedicated Asia Regional eSIM, which offers seamless connectivity across multiple territories.