Japan is an unusual eSIM destination. The underlying network infrastructure is outstanding — Docomo and SoftBank consistently rank among the top five mobile networks globally in Ookla's Speedtest performance reports. Indoor coverage in Tokyo is better than most European capitals. Shinkansen trains have in-cabin 4G coverage for most of the Tokyo–Osaka route. Even rural prefectures in Hokkaido have usable LTE outside national park wilderness areas.
But Japan's carriers have historically been restrictive about eSIM. Regulatory frameworks, carrier certification requirements, and the country's traditional preference for physical retail distribution created a situation where eSIM availability lagged behind the network quality. That situation has changed significantly since 2022. Here's the current state.
Which Carriers Support eSIM in Japan
Japan has three major national carriers: NTT Docomo, SoftBank, and KDDI (au). All three now support eSIM on their consumer plans. However, the eSIM support is primarily designed for their domestic contract customers, not for international roaming.
For international travelers, the relevant eSIM providers are the MVNO operators who have negotiated roaming access on Docomo and SoftBank's networks. These MVNOs act as the technical intermediary — the eSIM profile you install connects to the MVNO's network, which then routes traffic through either Docomo or SoftBank's physical infrastructure.
Truely's Japan coverage routes through Docomo as the primary carrier. Docomo has 48% of Japan's national market share and provides coverage across all 47 prefectures. SoftBank is available as a fallback for areas where Docomo signal is weaker — though in practice, Docomo's coverage is strong enough that fallback is rarely needed outside deep mountain terrain.
Network Performance: What You Can Actually Expect
In Tokyo, Osaka, Kyoto, Fukuoka, and Sapporo: download speeds between 50–150 Mbps on LTE are typical during off-peak hours. Peak-hour speeds in central Tokyo (Shibuya, Shinjuku, Ginza) drop to 20–50 Mbps due to network congestion, which is still fast enough for any practical use. Video calls on Zoom and Google Meet run without perceptible quality issues.
On the Tokaido Shinkansen between Tokyo and Osaka: in-cabin coverage is present for roughly 85% of the journey. The tunnels between Nagoya and Kyoto cause signal drops of 30–90 seconds each. Download speeds in the train are typically 15–40 Mbps between tunnels — adequate for email, messaging, and most work tasks.
In rural Hokkaido, Kyushu, and Shikoku: LTE coverage is available in all cities and towns with populations above 10,000. Smaller villages and hiking trails in national parks are a different matter. The Daisetsuzan and Shiretoko national parks in Hokkaido have no cellular coverage for significant portions of their trail networks. This is consistent across all carriers, domestic and travel eSIM alike — it's a network gap, not a travel eSIM limitation.
VoIP Restrictions: The Key Caveat
Japan's regulatory environment permits VoIP calls on mobile networks, unlike some Middle Eastern countries. WhatsApp calls, FaceTime Audio, Google Meet, and Zoom all work normally on Truely's Japan eSIM. There are no restrictions on these services imposed at the network level.
The caveat specific to travel eSIM plans — not just Truely, but most providers — is that voice calls routed through the eSIM's phone number are generally not available. A travel data eSIM provides data only. If you need a Japanese phone number for incoming calls (for hotel confirmations, restaurant reservations, or local contacts), the eSIM's data connection can route those through VoIP apps, but you won't have a +81 phone number assigned.
For business travelers who need to appear to call from a Japanese number, a separate local SIM is required. For most travelers who communicate via WhatsApp, WeChat, or email, this limitation doesn't apply.
Hotspot Sharing in Japan
Carrier policy on hotspot sharing varies. Truely's Japan plan explicitly includes hotspot functionality — this was negotiated as part of the carrier agreement rather than being an undocumented feature. You can use your phone as a mobile hotspot to connect a laptop, tablet, or other device to the Japan data connection.
That said, hotspot usage from a single device in Japan tends to attract network throttling at the carrier level more aggressively than in some other markets. If you're planning to run a full day of laptop work through a mobile hotspot in Japan, expect speeds to degrade from the 50–150 Mbps ceiling toward a more stable 10–30 Mbps after 30–60 minutes of sustained heavy use. This is adequate for most work tasks but worth knowing if your workflow requires large file transfers.
Practical Setup Notes for Japan
One specific quirk in Japan: some iPhone models sold in Japan have a restriction on simultaneous eSIM and nano-SIM operation that doesn't exist on the same model sold elsewhere. The Japanese version of iPhone 13, for example, has different SIM slot restrictions in its firmware than the US version. If you're traveling with a Japan-purchased iPhone, confirm the dual SIM behavior in Settings before departing, rather than discovering the restriction at Narita.
Truely's Japan eSIM should be installed before departure. The QR code for the Japan plan includes a carrier configuration for Docomo's preferred network access settings. Installing the profile in your home country (where there's no Docomo signal) has no effect on functionality — the profile simply sits inactive until your device connects to Docomo's network in Japan.
One non-obvious tip: in Japan's subway systems, cellular signals in most stations are very good. Between stations in tunnels, signal drops. If you're navigating by phone in Tokyo's metro, keep your directions loaded before descending into a station rather than relying on real-time route recalculation in a tunnel. This applies to all carriers, not just travel eSIM.
Purchasing a Truely Plan for Japan
Truely offers Japan-specific single-country plans and APAC regional plans that include Japan as one of eight covered destinations. For a trip to Japan only, the single-country plan offers slightly better per-day pricing. For trips that combine Japan with other APAC stops — Singapore, South Korea, Taiwan — the regional bundle is more cost-effective.
Plan durations start at 1 day ($4.99) and extend to 7 days ($9.99) and 30 days ($24.99). All plans include unlimited data and hotspot support. The 7-day and 30-day plans are the most commonly purchased for Japan itineraries — the country rewards spending time, and most first-time visitors stay at least five or six days.
Japan Without a Data Plan: The Risk
Japan is a remarkably convenient country for travelers with mobile data and less convenient for those without it. Train schedules, platform numbers, transfer guidance, restaurant queuing systems, Google Translate for menus — all of these are accessible via mobile data and become significantly harder without it.
Pocket WiFi devices are available for daily rental at Narita and Haneda airports. They work, and they're a reasonable option if you're sharing a data connection with a group. The downsides are the return logistics at the end of the trip (you have to return the device to a specified desk before departing) and the dependency on carrying an extra device. For solo travelers or small groups, a travel eSIM on each phone is simpler than sharing a pocket WiFi router.