Lang is a rather interesting character proposal I came up with not too long ago.
He is based on the Mansyū Ki-98, a ground attack aircraft under construction at the end of WWII in Manchuria, called Manchukuo under occupation. The use of the markings for the Manchukuo Imperial Air Force is his form of protest for his family's past treatment in China by Chinese - mainly as Manchus being associated with the deposed Qing Dynasty. Later still, his family was exiled for unfairly being portrayed as collaborators with the Japanese. Decades later, with a change in goverment, when he sought to visit his ancestial homeland, he was still denied, being told if wished to enter China, he would be punished for his family's 'treason'. Not willing to be used as a propaganda tool for events that were years before his time, Lang angrily dropped his travel request.
A few years later, when he became an Avian, he chose to model himself on the Ki-98. But as opposed to using the intended Japanese marking, he felt that the Manchukuo markings would be more appropriate for his heritage, and general Chinese markings would be demeaning to his family's past problems. As he grudgingly put it, "They want to view me as a traitor? Fine....I'll look the part." He openly stated he would change them, but not at the expense of his family name suffering any further.
Despite his controversial appearence and the reasons behind it, Lang activtely avoids confrontation and is known as a calm and courteous individual. While he laments his situation, he has gained sympathy by not expressing a hatred of those who continue to hold a grudge against him because of what is said of his family. He would prefer to make ammends and put the whole affair behind him, but feels it is a task he should not have to do alone.