simpleSIM does not offer a truly unlimited data eSIM for Japan. All of its Japan‑specific plans have a hard data cap, and the plans that carry “Unlimited” in their name provide a limited quantity of high‑speed data each day (for example, the eSIM Japan Unlimited – 3 days plan gives 2 GB/day and reduces speed to 512 kbps after the limit is reached).
If you need a large data allowance, simpleSIM’s fixed data plans are an alternative. For instance, the eSIM Japan 20 GB plan bundles 20 GB for 30 days, and the eSIM Asia 50 GB plan offers 50 GB for 90 days, covering Japan and additional countries. These fixed data plans are often more cost‑effective for travelers unless you anticipate using an extremely high volume of data.