Continuing the chain, here's some CG help - I haven't gotten all of them myself, but here's what I do know.
SPOILERS (as few as possible, but just in case):
First page, top left - you should get that one when going to his mansion for a job, with high friendship or love points, I think. I got in the matter of course of stalking him, but you might have not done the job enough or stopped doing it before the friendship or love points were high enough.
First page, all the way left, middle row - you can get multiple versions of this, so it should show up at some point. Can't think of anything special I did to get it, sorry.
First page, all the way to the right, middle row - sexy times! Keep using your mouth on him until the blowjob scene happens, and this happened eventually. This variation didn't trigger for me until Shuu was a dom, so that might have had something to do with it.
The other two are missing for me too, sorry. I just asked my friend who's playing as well and she said the one on the second page, top right, is one which comes after Shuu adopts a cat, which is news to me. Man, I want to see that.
END SPOILERS