And here we are, something I've been meaning to share for a very long time but didn't get around to doing until now. The first of six Gate Keepers 21 drama CDs! These six CDs flesh out the universe of the 6-episode OVA significantly and were very well-done. Each one is easily its own additional episode, extending the series to twice its original length and featuring cameos from many original series characters as well as answering many of the fans' unanswered questions.
If you're a Gate Keepers fan this is a must-get! Well, assuming you have a working understanding of Japanese anyway! Enjoy!