Thanks for your info, Yann, Brian ^_^
That cel itself has pressed meshlike markings along the top edge.
But I didn't see any Gainax or any other words anywhere.
It is larger than the standard size cel, 
roughly a lillte shorter than about the size of a 17in. monitor screen,
if you turn it sideways, no punch holes.
It comes with a background, no markings either.
One thing for sure is that it's very detailed.
So.... *sigh*

Thanks again, guys!  ^o^