OVA released by Shinsen:
http://a.scarywater.net/shs/%5BShins...5D.mkv.torrent

http://anidb.net/perl-bin/animedb.pl...anime&aid=6129
http://www.animenewsnetwork.com/ency...e.php?id=10222

I think this is a sequel to that first Extra Stage that dealt with the two chick combination of Mako and Sayuki (if not mistaken).