Pocket WiFi or eSIM for Japan?

This is the test that changes the answer for a group, and it is easy to overlook. Run your party through four scenes.

If none of these will happen — you genuinely move as one block, all day, every day — a router is a reasonable single purchase. If even one will happen regularly, plan for independent connections.

• Charge it overnight, every night. Treat it like your phone.
• Carry the power bank the provider includes, and charge that too.
• Know who holds it today. Hand-offs are where routers get left in hotel rooms.
• Do not leave it baking in a sunny bag.
• Watch the device count. Every phone, watch and tablet joined to it shares both the battery and the data.

Read battery figures as ranges, not promises. Japan Wireless currently states approximately 4-8 hours of continuous use and includes a power bank. Sakura Mobile currently states up to 20 hours, shorter with more connected devices or heavier use, and that up to 15 devices can connect while recommending up to five for a stable connection. Those are provider snapshots for specific units, not a guarantee for your rental on your day.

Unlimited is a marketing word, not a technical one. What you want to know is whether there is a daily high-speed allowance and what happens after it.

NINJA WiFi makes the point for us. Its current plan page lists four products all called Unlimited Plan, at 1 GB, 3 GB, 5 GB and 10 GB per day. The word and the number sit on the same line.

The restriction terms are in the notes rather than the plan name. Its 5G note states that excessive usage of 10 GB per day or 300 GB per month may bring a speed restriction to avoid congestion, and that a restricted connection brings no equipment replacement and no refund of service charges. Its Infinite Unlimited note states there is no data limit, but that excessive use within a period may bring restriction during peak hours.

So read the notes, not the plan name, and check three things before you pay: the daily allowance, what happens once you pass it, and whether being throttled entitles you to anything. The same logic applies to eSIM data plans.

Your landing time and the pickup method have to match, or you arrive with no connection at all.

Counter pickup depends on the counter being open, and hours vary by airport and terminal. Two paths remove the gamble: have the router delivered to your accommodation — Japan Wireless recommends this when you arrive less than two hours before a counter closes — or use a digitally delivered data-only eSIM. Do not assume a voice eSIM avoids ID checks or physical access-code collection.

Check two things for your specific rental. Where it can be returned: pickup and return are not always the same place. Japan Wireless allows a posted return, but its pickup counters do not accept returns, and it currently asks for a Japan postbox by 3 p.m. on the day after the rental ends.

Whether the return point is landside or airside: this is the trap. Sakura Mobile states that its airport counters are pickup-only and cannot accept returns, that the device must go in a postbox, and that the return must be completed before entering the restricted area after the security check. Once you are airside you cannot come back out.

The same page asks you not to hand the device to hotel or airport staff to return on your behalf, because they may not take responsibility if it is lost. A favour at the front desk is not a completed return.

An eSIM has no return step at all. For a tight or unusual departure, that is one less thing to fail.

A rented router is your responsibility and the terms are not a formality. Japan Wireless states that an unresolved fault can lead to a replacement sent using the next three days of accommodation details, so a loose itinerary makes replacement harder. NINJA WiFi's terms require immediate notice of loss or theft and may require a Japanese police or public-organisation certificate for compensation.

None of this is a reason to avoid a router. It is a reason to treat it as an item you must protect, report and return.

If you already own a travel router, renting one looks avoidable. In Japan it is not, and the reason is regulatory rather than commercial.

Radio equipment used in Japan has to meet the technical standards in the Radio Act, shown by a giteki conformity mark. Japan's Ministry of Internal Affairs and Communications publishes an exemption for equipment visitors bring themselves, and the exemption is narrower than it first appears:

• Your phone is generally fine. A handset that meets an equivalent international standard, and is contracted with an overseas carrier holding a roaming agreement with a Japanese operator, may be used on a Japanese carrier's SIM. The ministry states this for SIM use, not only for roaming.
• Wi-Fi and Bluetooth are capped at 90 days from the date of entry — phone and tablet Wi-Fi, tethering, and Bluetooth accessories such as earphones.
• A router you brought from overseas is not covered. Asked directly whether a foreign wireless LAN router can be used, the ministry answers that it may be used only if the router itself carries the giteki mark.

There are also band-dependent location rules: 5.2 GHz, 5.3 GHz and 6 GHz LPI are indoor-only, while 2.4 GHz, 5.6 GHz and 6 GHz VLP may be used indoors or outdoors.

So the practical position is that renting a Japanese router, or using an eSIM in your own phone, both sit inside the rules, while carrying your own router into Japan is the option that needs checking. The ministry publishes a visitor leaflet in eleven languages, English among them.

A router for the shared and SIM-free devices, carried by the family core that stays together. One eSIM for each adult who might separate. The router serves the devices that never wander; the eSIMs serve the people who do.

Do not shop for a best brand. Shop for the conditions that fit how your group travels, then compare current options against them.

• Lean eSIM if every phone is unlocked and eSIM-capable and anyone who needs to stay reachable might be elsewhere during the day.
• Lean Pocket WiFi if you carry SIM-free devices or locked phones and move as one group, provided someone will own the charging and the return.
• Lean hybrid if children or laptops need coverage but the adults need to be independently reachable.

The optional data-only comparison below contains a labelled Mobal affiliate link. It does not change the group-split test or make an eSIM suitable for a locked or unsupported phone. Compare the non-affiliate router providers in the sources as well. We do not name a best provider.