I’ve had a couple people look at that kanji. They all said generally the same thing.
Basically one side says: I have obtained a patent, or registered patent. Something along those lines
The other side reads: handmade good quality, and the company name kantou(kanto?) Riki
I’m going to my local sushi joint tonight, I’m good friends with the sushi chefs and they usually do all my translating for me so I’ll show them the pics tonight to see if they come up with the same thing.
On a side note I showed them this Japanese razor and Japanese natural stone thread. They were really impressed with the quality of stones and razors. They are all older (70-80) and they remember the barbers from their youth or seeing their grandparents with similar razors and stones. They keep asking me for more pictures any time I go in.