Japan eSIM Plans

Almost every travel eSIM for Japan roams onto one of the same three networks — NTT docomo, SoftBank, or au (KDDI). What differs between plans, and what almost nobody explains, is the country your traffic appears to come from. That is the exit IP, and in Japan it matters more than usual.

Our Japan plans come in three routings. Standard plans exit via Hong Kong and can use docomo, SoftBank, au and Rakuten, with 5G where available. The plans marked (IIJ) exit from inside Japan on NTT docomo, but top out at 4G. The plans marked (nonhkip) exit via Singapore on au (KDDI), with 5G.

If you only need maps, messaging, translation and social apps, any of the three is fine and you should simply pick on price and data. If you plan to use Japanese services that check where you are connecting from — some domestic streaming catalogues, ticketing sites, and banking or delivery apps — a Japanese exit IP behaves more predictably, which is what the (IIJ) plans give you. The trade-off is that (IIJ) is docomo-only and 4G rather than 5G.

5G is available across the major cities and most towns. Rural and mountainous areas are frequently LTE-only, and band n79 is concentrated in dense urban areas, so a 5G indicator in Shibuya is not a promise of 5G in the Japanese Alps.

For nationwide travel, docomo and au have the strongest rural reach — relevant if your route includes Hokkaido, Okinawa, or the mountain regions. SoftBank is strong in cities and slightly thinner rurally. Standard plans can use all four networks, which is the more forgiving choice for a long multi-region trip.

On the Shinkansen you should expect coverage to drop in tunnels regardless of which plan or carrier you choose. That is a property of the route, not of the eSIM.

Navigation, messaging and occasional social use tend to land around 300–500 MB per day. Adding regular photo and video uploads pushes that towards 1–2 GB per day. Streaming video or tethering a laptop moves you into 3 GB+ per day, and at that point a daily-allowance plan is usually better value than a fixed bundle.

Two structures are available. Fixed bundles (for example 10 GB over 30 days) let you use the data at whatever pace you like — good for uneven trips. Daily plans reset every 24 hours, which suits consistent everyday use but means unused data does not carry over.

Plans labelled FUP1Mbps do not cut off when you pass the daily allowance; they continue at reduced speed. That is workable for maps and messaging and frustrating for video.

Install the eSIM before you fly, while you still have home Wi-Fi. The profile downloads over the internet, and doing it at the airport on arrival is the most common avoidable problem.

Japan requires device registration for some MVNOs. Our plans connect through the major carriers, so there is no additional paperwork on arrival.

One genuine deadline: the plan must be activated within 30 days of purchase. Buying months ahead of a trip is the mistake to avoid — buy within a few weeks of departure.