Majestic Prince - Season 1 Episode 9 Disclosure

Despite having the upper hand, the Wulgaru retreat, leaving heavy casualties on Earth's side. Izuru, in shock upon realizing the true nature of their enemies, is instructed by Rin to not reveal it to the others. Soon after, he has another encounter with the mysterious girl, and much to their surprise, Team Rabbits is informed that she is a Wulgaru who had warned mankind of the attack from their race, and their mecha were created using Wulgaru technology obtained from her.