Looking further at the description of these lines I saw this statement - " All “GT line” is handmade by Daisuke Tsuchiya . …"
Since I know that " Ya" 屋 , is a word meaning store or shop. I was thinking Daisuke Tsuchiya is maybe the name of a company. And set about searching the internet for the company with various phrases such as : 土屋大介のテーパーライン手作り, Tapered line handmade by Tsuchiya Daisuke.
But soon discovered that Tsuchiya Daisuke is not the name of a company, it is the name of the owner of the Go Tenkara Ground Store. 土屋大介さん ( Tsuchiya Daisuke-san )
Anyway, the search found the below webpage, which I have seen before in recent years, It’s a fun page to read. With both Japanese and English translation. The internet search found the webpage because the name Daisuke Tsuchiya, and 土屋大介 are in the paragraph just below the picture of the Tenkara Rod Co. rods on the webpage. Maybe you will enjoy it too.