I remember being intrigued by Mick Karn's sound, when I first heard Japan and this encouraged me to get a fretless bass and try to emulate that style - with varying results!!
Then there was an interview with him in "International Musician" Magazine (Bass Player didn't exist then!) - which asked him about his sound.
So - he explained how in Japan, David Sylvian would write tunes and record them with Richard Barbieri and then Karn would add bass lines - but invariably they were out-of-tune and out of key.
However Sylvian and Barbieri, liked this chaotic element and as they always started out with just keyboards, they were able re-tune and re-programme to fit Karn's line - so they actualy rebuilt the song around Karn's out-of-tune fretless bass lines!!