Wow. Super cool old funky bass. Looks like probably early to mid 60's. Maybe Matsumoku, but the pots are different for what they did.
Kawai Teisco was founded by Atswo Kaneko and Doryu Matsuda. The company also produced the popular Ibanez badge in the 1960's. Kawai Teisco made their own house brands Kawai, Teisco, Del Rey and Teisco Del Rey. Badged guitars produced by the Kawai Teisco factories include Apollo, Aquarius, Arbiter, Atlas, Audition, Avar, Ayar, Barth, Beltone, Black Jack, Cipher, Concert, Cougar, Crown, Daimaru, Decca, Diasonic, Domino, Duke, Emperador, Heit Deluxe, Hy-Lo, Holiday, Imperial, Inter-Mark Cipher, Jedson, Kay, Kent, Kimberly, Kingsley, Kingston, Keefy, Lindell, Marquis, May Queen, Minister, Noble, Prestige, Randall, Recco, Regina, Rexina, Sakai, Satellite, Schaffer, Sekova, Silvertone, Sorrento, Sterling, Swinger, Tele Star, Top Twenty, Victoria, and Winston. Possible badged guitars made by the company include: Astrotone, Demian, G-Holiday, Lafayette, Master, Orange, Tamaki and Trump."
Here is another Black Jack I found... http://hubpages.com/hub/Japanese-Man...m-1950-to-1980