Rakuten Mobile's au roaming is ending. What changes? Facts and views, kept separate

“Rakuten Mobile’s au roaming is ending.”

A lot of people probably saw that in the news and felt uneasy.

“So… will it still work where I live?” Yeah. That’s the natural reaction.

One thing up front: this site uses Rakuten Mobile referral links. Even so, I won’t hide the parts that are bad for Rakuten.

I’ll keep facts and other people’s views separate.

The 30-second version

• KDDI’s roaming for Rakuten Mobile: the old framework ends at the end of September 2026
• From October, roaming stops in areas Rakuten has built out itself
• How much it affects you depends on your area. The surest way is to check your daily routes on the official map

What is roaming? Borrowing someone else’s road

Rakuten Mobile has been expanding its service while building out its own base stations.

Where its own base stations don’t reach yet, it has filled the gaps by borrowing KDDI (au)‘s network. That’s roaming (the partner network).

Think of it as training wheels on a bike.

Until its own coverage grew, it was being propped up by another company’s equipment.

Now those training wheels are coming off.

What was decided (the facts reported)

According to a Keitai Watch report (September 30, 2026), here is what we know.

• KDDI published the map of roaming areas for Rakuten Mobile from October
• Roaming under the old framework ends at the end of September
• From October, roaming stops in areas Rakuten has built out itself
• Elsewhere, Rakuten building base stations is described as a “basic premise”. In some regions only, KDDI will help maintain the infrastructure for a certain period
• The areas where roaming is provided will gradually narrow
• Roaming has already ended in Tokyo’s 23 wards, Nagoya and Osaka

The map lets you toggle between “until the end of September” and “from October”. It shows that roaming areas shrink sharply in cities such as Yokohama, Hiroshima and Fukuoka.

Note that the body of this report doesn’t give figures such as population coverage or the number of base stations.

How much will it shrink? (a column’s rough estimate)

You want numbers, right?

A column, also from Keitai Watch, gives a rough estimate based on the published maps.

• It had Claude read the images of KDDI’s published maps (until the end of September and from October) and calculated the decrease in roaming area
• Across the 18 government-designated cities combined: from about 4,460 square km to about 2,820 square km, a decrease of about 37%
• The national average is a decrease of about 20%. Cities are hit harder
• Kobe has the largest decrease at 59%, followed by Yokohama, Saitama and Chiba, all around 50%

This part matters, so I’ll say it plainly.

These figures are rough estimates from analyzing the colors in map images. They are not official numbers. The column says KDDI’s PR declined to answer on details such as the share of areas being switched off or the number of base stations.

Also, the areas being cut are the ones where Rakuten says it has its own coverage. In places where Rakuten’s own coverage isn’t built yet, such as mountain areas, roaming continues.

The concern: “full bars, but no data”

The column’s author expects that from October, places where the antenna icon shows bars but data doesn’t flow will definitely increase across Japan.

This is the author’s view. It is not an established fact.

As a general point, the bars on your phone and whether data actually flows are two different things. Even with a signal, if the equipment lacks capacity, connections can slow down or drop.

The author also thinks that in Kyoto, landscape ordinances make it hard to install base stations, so it won’t be easy for Rakuten to take quick countermeasures.

On the other hand, the author also writes that KDDI users may see better communication quality.

What you can check yourself

Stirring up anxiety doesn’t help, so here is what to do.

① See which side your daily area falls on

Compare your home, workplace and commute route on KDDI’s published roaming area map (until the end of September / from October) and on Rakuten Mobile’s official area map.

② Test the connection in your usual places from October

Use video and map apps normally at home and at work. Judge by whether data actually flows, not by the bars.

③ Check which bands your phone supports

Whether Rakuten’s own network reaches indoors also depends on which Bands your phone supports. I’ve put how to check in a separate article on this site (phone Band compatibility check).

Rakuten is taking steps too

The part roaming loses has to be filled by Rakuten’s own base stations.

• The low-frequency platinum band (700MHz) is better indoors and in suburban areas. I explain how it works in a separate article on this site (platinum band explained)
• Rakuten Mobile has announced it will introduce a system where AI automatically adjusts antenna tilt, the idea being that nearby stations cover the hole when a base station goes down. I wrote about it in a separate article on this site (physical AI antenna)

That said, with the information available now, we can’t tell how far these will make up for this shrinkage. The only way to judge is by measuring in each area.

Summary

• au roaming under the old framework ends at the end of September 2026. From October, roaming stops in areas Rakuten has built out itself
• There is a rough estimate of about 37% shrinkage in government-designated cities and about 20% on the national average, but it comes from image analysis and is not an official figure
• The concern that places with “bars but no data” will increase is the author’s view. It is not an established fact
• The impact depends on your area. Check your daily area on the official maps and judge by actually using it

If you’re thinking of signing up, check first whether your home and workplace are in Rakuten’s own coverage, before you sign the contract. Choosing with the downsides in mind means fewer regrets later.

Source: Keitai Watch

• Rakuten Mobile au roaming: area map from October published (September 30, 2026) (in Japanese)
• au roaming for Rakuten finally ends, urban areas may drop by about 40%. Exploring the impact on communication quality through maps (September 30, 2026) (in Japanese)

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