KDDI (au) is one of the networks your eSIM may use in Japan. Here is who actually decides which network you get, and what to do with that.
Quick answer
KDDI (au) shut down its CDMA 3G network on 31 March 2022; its network now runs on 4G LTE and 5G.
| Item | au (KDDI) |
|---|---|
| LTE (4G) | B1, B3, B5, B11, B18 |
| 5G NR | Not verified |
| 5G launched | Live |
| 3G | Shut down |
| Network code (MCC-MNC) | 440-50, 440-51, 440-52, 440-53, 440-54 |
Checked against the sources on 2026-10-12. Only the bands a source confirmed are listed; the network may run others too.
An eSIM can only use au (KDDI) if your phone supports at least one band in this table. Before you fly, open your model's spec page on the maker's site and compare its LTE and 5G band lists.
au (KDDI) publishes its own coverage map. Look up the street or district you will stay in rather than the country as a whole, because coverage in town and out of town differs a great deal. The map shows au (KDDI)'s own network; a roaming plan may not get every technology it shows.
Mobile networks in Japan are licensed, and their spectrum assigned, by the Ministry of Internal Affairs and Communications (MIC). The bands above are the ones it allocates. A problem with the local network's own service goes to the operator first; a problem with your eSIM plan comes to us.
From the supplier record behind each package, 105 of the 117 plans we currently sell for Japan declare KDDI (au) as a network the profile can reach, at 4G and 5G. The figure comes from the same catalogue that prices the plan pages, and it moves when the supplier revises the record.
| Network | LTE bands | 5G bands |
|---|---|---|
| KDDI (au) | B1, B3, B5, B11, B18 | Not verified |
| NTT DOCOMO | B1, B3, B5, B19, B21, B42 | n78, n79, n257 |
| Rakuten Mobile | B3, B28 | n77 |
| SoftBank | B1, B3, B8, B11, B28, B41, B42 | n3, n28, n77, n257 |
A band shared across networks is one a single phone can use on all of them.
Nearly every travel eSIM is a roaming product: the profile picks a network by an order the supplier sets, not by the buyer. If KDDI (au) is weak where you are, try selecting NTT DOCOMO or Rakuten Mobile or SoftBank manually in the network settings, and keep data roaming on for the eSIM profile.
105 of our plans name KDDI (au) as reachable, but that is not a guarantee. Travel plans run over roaming agreements, so the network depends on the supplier behind the plan, your device and where you are.
At least one of these, LTE: B1, B3, B5, B11, B18. Your phone's band list is on the maker's spec page for your model, under "Cellular" or "Network".
Yes. au (KDDI) has run commercial 5G. A travel plan only gets it when the plan permits 5G, your phone supports one of those bands, and you are inside 5G coverage. Miss any one and you fall back to 4G.
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.
Porsch Kunnipat Siramanakul
Instagram and TikTok have no web share button, so we open your phone's share sheet or copy the link instead.
Ranked by our value score. Each plan page lists the networks its supplier declares.
NTT docomo / Rakuten Mobile / KDDI/au
Exits in Hong Kong · NTT docomo / Rakuten Mobile / KDDI/au
Validity starts on first connection at the destination
NTT docomo / Rakuten Mobile / KDDI/au
Exits in Hong Kong · NTT docomo / Rakuten Mobile / KDDI/au
Validity starts on first connection at the destination
KDDI/au / SoftBank
Exits in Singapore · KDDI/au / SoftBank
Validity starts on first connection at the destination
NTT docomo / Rakuten Mobile / KDDI/au
Exits in Hong Kong · NTT docomo / Rakuten Mobile / KDDI/au
Validity starts on first connection at the destination
KDDI/au / SoftBank
Exits in Singapore · KDDI/au / SoftBank
Validity starts on first connection at the destination
NTT docomo / Rakuten Mobile / KDDI/au
Exits in Hong Kong · NTT docomo / Rakuten Mobile / KDDI/au
Validity starts on first connection at the destination
