Every trip has a shape, and the right eSIM plan follows it rather than the other way around. Buy too narrow a plan and a day trip across a border leaves you stranded; buy too broad a one and you've paid for continents you never set foot in. Here's how the three shapes actually differ, and which one fits which trip.
Country plans: one destination, nothing wasted
A country plan covers exactly one place - Japan, and only Japan, for the length of your stay. It's the cheapest way to buy data per gigabyte, because you're not paying for coverage you won't use, and it's the obvious choice for the most common trip shape: fly somewhere, stay put, fly home. If your itinerary has one stamp in the passport, a country plan is very hard to beat on value.