Saily does not provide a truly unlimited data eSIM for Japan. All plans that use the word “UNLIMITED” in their name actually give a set amount of high‑speed data—5GB per day or 30GB for the month—and once that limit is reached the connection is throttled to a reduced speed, which ranges from 1kbps to 1024kbps depending on the plan.
If a traveler needs more data than the daily limit, Saily offers fixed‑data alternatives. For example, the Japan 20GB 30 days plan gives a single 20GB allowance over a month for about $24.99 USD, and the Japan 30GB 30 days plan provides 30GB for about $71.99 USD. While these plans are not unlimited, they may be more cost‑effective for regular users who want a predictable data allotment.