S&M?
Well if you don't count hentai there is probably close to zero actual S&M manga like such. Although there are various ecchi manga that have an S&M girl or episode.
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Personally though, I got enough of S&M outta Ichi The killer(Warning: Adult content in all areas).
As far as S&M Goes though, Hentai(doujins) will deffinitely be more wide-ranged in that area. S&M isn't really meant for non-hentai anyways though.