Real Wasabi is insanely water-intensive. This is where I first read about it:
https://www.theatlantic.com/video/index/585172/wasabi-fake/
There is a NZ brand which has cracked cultivation. It is not cheap.
ETA: I have not tried it. Saving the purchase for when I can talk my wife into sushi from my wild catches. Tall order.
Take good care of parasites. The deep frying of stor bought fish is also a parasite treatment, so is cooking. Wild catch needs detailed knowledge for the specific species, if and how it needs inspection and if and how it can be eaten uncooked and unfrozen, ie completely raw.
Wild catch is not just in and by itself "good and healthy"
This article has some sound references at the end:
Our next freezer will be of the requisite grade.
Local fishing charters here like to dice up fresh salmon or trout on the boat as sashimi. I reckon their customers stay thin, if you follow my meaning.
Also, some fancy sushi chefs let the fish age a while at very low temps. See: Naomichi Yasuda
I’ve had plenty of both but I generally enjoy the sharper heat of the latter more, even though it annoys me that it’s mislabelled and hence a bit “fake”.
Ask for it at higher priced places where they take a little more care about the fish quality and eventually you're bound to find some. Like so many things it's good to know the difference at least once. It's no huge loss if you only eat the horseradish the rest of the time, but at least have experienced it once!
There’s definitely filler (more than 50% is real)but I don’t think people care, especially the average busy wife trying to get dinner on the table every day.
Most of the time I’ve had real wasabi its at a super nice place, like eating kaiseki, and it’s presented as the root with a small shark skin grater.
>> 原材料名: 本わさび、西洋わさび、...
...except the everyday stuff shown in your link indeed contains substantial 本わさび as a first ingredient, whereas the typical stuff sold in the US[1] is effectively just 西洋わさび and happens to be explicitly labeled "For external Japan" (despite also being manufactured in Japan) for reasons.
In other words, a consumer in Japan who settles on "close enough" isn't really making an equivalent compromise as a consumer in the US.
[1] https://www.sbfoods-worldwide.com/products/search/001.html