Think he just said he was natural to other Japs, yes ive heard a few stories too, but it doesnt matter and asking his family wouldnt be right, its nice that at Golds Otsuka they have his workout gear framed on the wall, big dude in his day.
I have the feeling as well, a lot of guys come to me to talk about gear in the gym, but i have never heard them talk about gear among each other, then it's always: Damn, Suzuki is so big, he is super strict with his diet and trains hard, a Mr Nippon would NEVER use steroids.
Mr Nippon is untouchable, another guy in the gym struggled hard to reach 100 kg offseason, very bloated and people would jokingly say to me "all the GH and steroids and he's still small"... Obviously he wasn't on GH, and by no means small, but there you go.