merdata does not provide an unlimited data eSIM plan for Japan. Its available options for the country are fixed data plans, such as the eSIM Japan 50 GB 30 days plan and the eSIM Japan 50 GB 180 days plan. These plans give a set amount of high‑speed data that must be consumed within the specified validity period (30 days or 180 days).
The fixed data plan format can be more cost‑effective for most travelers, especially those who do not need unlimited data. If a user requires very high data usage, they can choose a plan with a larger data cap, such as the 50 GB options listed above, or combine multiple plans to meet their needs.