Some reason there was only song (I didn't find opening video, but song is pretty nice too).
It's new series of Genshiken. Before this there was Genshiken (from 2004)
and Genshiken 2 (from 2007). I must watch those two again because it's pretty longtime when I saw those and I'm pretty sure that I never finished them.... gehehehe (well maybe Genshiken but not sure about Genshiken 2..). Oh well! Nidaimen was really good one and I'm sure that it's not a problem if you haven't seen those two before this... but it would be nice to see where everything started though (or so I think) ^^'
And I must put this (because Snk!) here, it's not spoiler but it's from last episode and... well watch and see! But you must have seen Shingeki no kyojin to understand this though ^^'