So it appears that Oreimo was spared of a lacking ED sequence as the official website has started streaming the actual ending sequence that was absent on TV for some strange reason (guessing it was something along the lines of time constraints). Apparently so this was meant to have been shown at the end of the first episode.
It’s called “Imouto Please!“(Sister Please!!) performed by Ayana Taketatsu, the seiyuu for Kirino.
At some point when watching the ED I had a vague feeling that I was listening another K-ON! character song sung by Azu-nyan, since Taketatsu-san also voices Azusa if you didn’t know.
A special trivia; “Imouto Please!” was originally sung by the Vocaloid Hatsune Miku and proved to be much popular on the Nico charts. As can be seen below ripped onto YouTube;
Overall, I think it’s a nice upbeat song in terms of Kirino’s, but seems much more natural and smoother with Miku’s version. But in this case, I gotta side with Kirino’s version just this once since for once I like Taketatsu’s singing voice compared to the mediocre type of singing in the K-ON! albums with her in.
No idea if they are ever gonna plan to put this into the TV run but most likely going to edit this ED into all eps when it comes to the BD/DVD release.