There's plot, but there's sex. Tons of sex. In every doujin.

And it's probably about as graphic as Yamane Ayano (Viewfinder, Crimson Spell), but I think it might be that the magazine Yoshinaga was publishing in wasn't an explicit one...? I dunno. Anyway, they were released as doujin--all of them are pretty short, anyway, and though they kind of follow a plot, I think (though I'm not sure, as I can't find them scanlated) that they can each stand alone as well.