"First harvest" appears on a lot of matcha tins. It is one of the few terms in this category that means something specific, which is exactly why it gets borrowed by tins that have not earned it.
Here is what it actually refers to.
One plant, several pickings
A tea bush is not harvested once. It is picked in waves through the growing season, and Japanese has a plain name for each one.
Ichibancha is the first picking, in spring, usually late April into May depending on the region and the year. These are the leaves the plant grew over winter, using everything it had stored.
Nibancha is the second picking, early summer.
Sanbancha is the third. Each round comes from a plant that has already given away its best material and is now regrowing in heat and strong sun.
First harvest matcha is made from ichibancha. That is the whole claim. It is not a quality rating, it's a date.
Why the date changes the taste
The difference comes down to what the leaf was doing before it was picked.
Over the winter the plant moves amino acids, mostly L-theanine, into the leaf. L-theanine is what makes good matcha taste savoury and sweet rather than sharp. Spring leaves are dense with it.
Then the tea is shaded for two to three weeks before harvest. Shading slows the plant down and keeps it from converting those amino acids into catechins, which are what make tea taste bitter and astringent. Less sun, less bitterness, more umami.
By the second and third pickings, the plant is growing fast in full summer heat. The leaves are coarser. The amino acid content is lower and the catechin content is higher. You can still make matcha from them, and plenty of matcha is made from them. It is simply a different drink: sharper, flatter, more obviously bitter, and much better suited to being buried under milk and sugar than drunk on its own.
There is also the physical leaf. Ichibancha leaves are young and soft, and they grind into a finer powder. Later leaf is tougher, and it shows up as a coarser texture and a duller colour once it is in the bowl.
What it does not tell you
First harvest is necessary for good ceremonial matcha. But, it is not sufficient.
It says nothing about where the leaf grew. It says nothing about the cultivar, or whether the plants were shaded properly, or whether the leaf was stone-milled slowly or blasted through a machine mill. A first-harvest leaf from a mediocre field, milled carelessly, will make a worse bowl than a well-handled second harvest.
It also says nothing about when. Matcha does not improve on a shelf. First harvest from three springs ago is still first harvest, and it is also stale.
So the term is a floor, not a ceiling. It rules out the worst material. However, it does not confirm the best.
How to check whether a tin means it
Look for a harvest year. If a brand is genuinely selling ichibancha, the spring it came from is a selling point, and they will print it.
Look for a region and ideally a garden, not just "Product of Japan." First harvest from an unnamed source is a claim nobody can check.
First-harvest leaf costs several times what later pickings cost at auction, and that has been more true in the last two years than ever. A tin claiming first harvest at a supermarket price is claiming something the arithmetic does not support.
Taste it plainly whisked with water, no milk. Later-harvest matcha hides well in a latte because it has nowhere to go in a bowl of usucha.
Where MAJICHA sits
Everything in our ceremonial line is ichibancha from a single garden in the Uji region of Kyoto, stone-milled. One picking a year, from one place.
It is a narrow way to run a tea business and it is the only way we know to get the bowl to taste the way it should.
