Team Pied Piper is assigned to take part in a special festival in Switzerland as part of Generation Bleu's public relations policy, but Fleur and Elena have Ao dress up as a girl much to his chagrin. At the festival, the trio find themselves running away from an insistent journalist until they are called back to confront a Secret that appears on the border of Italy.
This cute little OVA fits chronologically somewhere in the main narrative as a "side story"; it is pure "fan service" in the broadest sense of the term. The female pilots tease Ao and make him dress up...like his mother! and Ao in drag is drawn very convincingly like Eureka from the original series. They even throw in a Ranma 1/2 visual gag for fun. Basically the trio of mech pilots are on leave and enjoying a brief vacation between missions. They goof off and have fun with each other. The animators probably had fun switching between obvious Ao in drag and straight up Eureka in terms of character designs...it really works. It's a comedic one off and very light in terms of story, but it's just a fun diversion to be enjoyed separately from the main series.