The airport counter is a battery you return. That is the product.

One radio in a bag works if everyone stays inside its range. If two people take different trains, the person without the brick has no maps.

eSIM is one plan per phone. No return. Airalo Japan unlimited (copied 29 Aug 2026): $27 for 7 days, 3GB/24h then 1 Mbps. Holafly 7 days $27.50, hotspot 1GB/day. Ubigi 10GB/7 days $14 on Docomo/KDDI.

Group of 3+ who never split: one pocket Wi-Fi can still be cheaper. Solo or a couple that splits: eSIM.

Dated comparison: https://before-you-land.tiiny.site/japan/pocket-wifi/

Airalo checkout there is affiliate. I do not hide Ubigi.