A café "date" with your best friend was all you needed today. You wanted to share your news with Atsuhiro about what happened today. When the both of you ordered your coffees, you started explaining the situation to him about how you met Mr. Compress.
"Wait.. What do you mean he just gave you two marbles that decompressed into a pretty boquet of flowers because he thought you were pretty? And then he just disappeared?" Atsuhiro had to act confused, when he knew exactly what happened. He was there. He was the one who made this all happen.
But he couldn't afford to tell you he was Compress, since as a villain he had to keep his identity a secret, even if you are his best friend that he developed unwanted feelings for. All he can do is watch you fall for his other persona, like it was another person.