Two I know and can read. The first kanji could be read as 'one hundred'. The middle one is 'book', or it works as a counter. The last one doesn't show up in the dictionary.
I've noticed most quality matcha whisks come with a sticker like this. Is it the crafter's signature or something? The website I bought from had no information other than to tell me it was made from organic bamboo and to give care instructions.
Do forgive the question but when I'm learning, all rabbit holes must be searched after I've fallen in!
If you are planning on making matcha with a bamboo whisk, I recommend also using a fine strainer/sifter when putting the matcha power into your bowl. It will help tremendously with clumping. If you are already aware of this tip, just ignore this post :)
I've been to a matcha mixing and tasting event in the past, which was incredibly fun. I don't own a strainer, but I've found that the whisk I have works well enough, and I've never noticed any clumping, thankfully!