KT Japan said on Monday it is launching tt mobile, an MVNO service that allows South Korean customers planning long-term stays in Japan to apply for a Japanese phone number in Korean using only a passport before departure.

With the launch of tt mobile, KT Japan will expand its business portfolio for individual customers such as students, working holiday visitors and expatriates, in addition to its communications services for Japanese corporate clients.

KT Japan said customers can apply for a Japanese phone number before departure using only a passport and PASS simple authentication. Customers complete the sign-up process in South Korea, receive a USIM, and then only need to request activation after arriving in Japan to use a Japanese phone number on the NTT Docomo network. Fees can be conveniently paid with a card issued in the subscriber’s name in South Korea.

The company said tt mobile can be subscribed to with a passport and is offered in 2 types: a working holiday and student plan and a business plan.

Under both plans, users can continue to use data at speeds of up to 200 Kbps even after they have used all their allotted data.

KT Japan also operates a basic plan for residents of Japan. It can be subscribed to with a My Number card, and users can choose among major Japanese carrier networks including NTT Docomo, KDDI and SoftBank.