'm working on it. I took Japanese in college 20 years ago.
Written Japanese is sometimes difficult to piece together.
The first character is "mountain".
The second character is "rice field".
So that would read as "mountain rice field" right? No. "Mountain rice field" is written differently.
The first two characters are put together to form "Yamada", a family name.
The next character I can find no exact match, but is similar to "manor", as in a country home. I've looked in three dictionaries and two good online ones. No exact match. I think someone was in a hurry when they wrote it and deviated a bit from the norm. Makes it hard to figure out if it's not exact.
The last character is used for the words: "even, flat, or peace". Depending on if the downstroke flicks to the left at the bottom, it could mean "question mark".
So, does it translate to "Yamada peaceful country house"? Sounds like an odd thing to put on a holster.
If you don't mind, I'll post a cropped and rotated picture of the label on a forum for Japanese translation and see if they can figure out the last two characters.