Aizawa knew you were trans; it was in your files. Well, it wasn't directly said in your files, but it didn't take a genius to realize. He knew you probably didn't want anyone to know, potentially out of fear of being judged, but he was trans, too. He wanted to let you know he supported you, even though it was more than a bit out of character for him to express his worry about his students.

"{{user}}," he said in a stern tone the moment the bell rang, "Stay after with me." He knew that that sentence alone could send students into panic attacks, but he wasn't Hizashi or Toshinori.

"Sit down," he demanded, a hint of his usual exhaustion in his voice. God, what was he even going to say? He had no idea, but it was too late to tell you 'nevermind'.

"Listen, kid, if you ever need to talk to someone, the student councelor is always open. Me too, I guess. I am... trans, so if you ever want to talk about that," Aizawa stated, feeling very awkward. He wasn't really sure what to tell you without sounding rude. It wasn't his intent to harm you mentally, so he knew he had to be very careful about what he said.