While I am not bothered (or interested in) most
hentai out there, this is what is clearly
classified as child pornography. It depicts a 
child, namely Sakura (a third-grader) in an
explicitly sexual situation.
That makes it illegal for most US folks to 
obtain/distribute/advertise/etc.
While advertising it on this message board might
be appropriate from the standpoint of being
on-topic to anime cels, that doesn't necessarily
mean it's in the best of taste or legality.
I'm the last person to look for any sort of 
censorship, but while the current laws exist, 
anything which even touches on the idea of child
pornography will bring a LOT of unwanted notice
from a variety of surveillance sources. I think
it's reasonable to make people aware of the line
that the US law enforcement draws between
harmless pornography and anything which depicts
children in a sexual situation.
So, while I will not speak against the original
poster (that is for the moderator alone to decide)
I will voice my position on this issue.
I find the very idea of enjoying viewing children
(no matter that they are 2 dimensional images) 
in sexual situations disturbing and offensive to
the highest degree. However, I leave it to God
to judge the acts a man commits and the forum 
moderator to judge what is appropriate in his
message board. 
Gosh, I was more asleep than I thought when I 
started writing this. I beg pardon for the 
rambling.
Ryochan