Sorry, I don't know any in Yokohama. Most of the ones in Tokyo seem to be centred in and around Shinjuku. This web site lists many all over Japan, which would have been particularly useful on my last visit had I known about it!
http://www.jazz-clubs-worldwide.com/docs/japan.htm about 8 years ago
Lentracte Charlies Jazz Bar
2-15-4, Yokohama, Kanagawa
Take Lift to second floor and take stairs to third floor
5 Min walk from Shin Yokohama Station
Across the road from the museum almost 5 years agoAnswered by Gary via WorldNomads.com