Custom Audio Japan (CAJ) is a Japanese guitar electronics brand established in 1991 by distributor Okada International under the supervision of Bob Bradshaw, founder of Custom Audio Electronics (CAE) in the United States. The brand was created to bring the same caliber of custom rack-based guitar rigs that Bradshaw had built for artists like TOTO, U2, and Aerosmith to Japanese musicians, and has since outfitted prominent Japanese acts including B'z, THE ALFEE, and Lindberg.

CAJ's catalog centers on signal routing and utility gear for guitar rigs. Notable products include the Loop and Link series of audio loop switchers, the Effects Loop Interface (designed by Bob Bradshaw) for integrating outboard time-based effects with amp effects loops, and MIDI controllers geared toward use with modeling systems such as Fractal Audio hardware. The brand also produces power supplies, DC distribution hubs, AC/DC converters, and a line of guitar and patch cables, including the Legacy Cable.

While CAE in the U.S. focuses on amplifiers and larger custom rigs, CAJ's identity is closely tied to pedalboard-level tools, cabling, and switching solutions aimed at both touring professionals and hobbyists. The brand is distributed in Japan by Okada International, based in Yokohama.

Custom Audio Japan has 10 products cataloged on Equipboard, including Effects Pedal Accessories, Switch Effects Pedals, and Tremolo Effects Pedals. Their gear is featured by 8 artists, with the strongest followings in Rock, Pop, and Stage & Screen. Notable users include Tom-H@ck, Yusuke (Lynch), and Takeshi Taneda.