KDDI (au) and travel eSIM in Japan

88 of our plans name KDDI (au) as reachable, but that is not a guarantee. Not necessarily. Travel plans run over roaming agreements, so the network depends on the supplier behind the plan, your device and where you are. KDDI (au) is one of the networks operating in Japan, not a guarantee attached to any particular plan.

Check the carrier name at the top of the screen, or open the mobile-network settings and look at the operator list. If signal is poor, try selecting a network manually instead of automatic — but only one your plan actually supports.

From the operator information we track, KDDI (au) runs 4G and 5G. Getting 5G in practice needs three things at once: the plan permits it, your device supports it, and the area has coverage. Miss any one and you fall back to 4G.