I only watched the ending credits.. (^_^;
Only 4 of the 12 main girls appeared so far.

Sister Princess
 Karen           :: Kuwatani Natsuko {episode 1}
 Kaho            :: Mochizuki Hisayo {episode 1}
 Sakuya          :: Horie Yui {episode 1}
 Hinako          :: Chiba Chiemi {episode 1}
 Wataru          :: Nojima Kenji {episode 1}
 Yamada Taro     :: Yamaguchi Kappei {episode 1}
 Mami            :: Hikami Kyoko {episode 1}
 Jiiya           :: Tsuchiya Toshihide {episode 1}
 girl            :: Nogawa Sakura {episode 1}
 Marie           :: Yuzuki Ryouka
 Chikage         :: Kawasumi Ayako
 Yotsuba         :: Hanba Tomoe
 Haruka          :: Kakazu Yumi
 Rinrin          :: Kanzaki Chiro
 Mamoru          :: Kobayashi Yumiko
 Aria            :: Mizuki Nana
 Shirayuki       :: Yokote Kumiko

--
Hitoshi Doi                                               Toshi Nibunnoichi
half a UFO catcher doll, half a cel          801 tactical training squadron
http://www.win.ne.jp/~doi/                                    doi@win.ne.jp