I was just there last week. Ochanomizu, in Tokyo, is to guitar players what the Playboy mansion is to straight men. If you ever have the chance, go. Just leave your credit card, wallet and first born at the hotel. Otherwise they are not safe!
My (admittedly very limited) dealings with Japanese guitar vendors have always been top-notch. The language issue has occasionally been a hurdle, but in terms of quality and service, I've been very impressed.
"Used" in relation to gear in Japan is an incredibly relative term. People take care of their gear really well, so often 'used' can mean 'NOS with a minuscule scratch.' It's very hard to find 'beater' guitars for sale in Japan because so few people beat on them, and when they do, no one else will buy them.
I bought an Edwards LP copy that should have been 83,000 yen but was marked down to 59,000 for a scratch I could never find, and for fingerprints.
I think you'll be happy with Ishibashi.