IS: Infinite Stratos 2 1x6

After losing against him in a practice bout, Ichika has a training session with Charles, which is interrupted by Laura who wants to fight him, but refuses. On his way back, he spots Laura talking with Chifuyu, begging her to return to Germany and that the IS Academy doesn't deserve her, but the latter doesn't listen. It is revealed when Ichika was kidnapped during the 2nd Mondo Grosso IS championship, Chifuyu forfeit the finals in order to rescue him. Upon returning to his dorm, Ichika walks in on Charles in the shower to discover he is actually a girl. Charles reveals she is her father's illegitimate daughter who was taken in after her mother passed away and made an IS test pilot. But when the Dunois corporation entered a financial crisis due to the demand for third generation ISs, Charles was ordered to act as a boy to give the company publicity and steal data from Ichika.