Famous Character Cosplay
This easter egg can be found in Episode 5 titled, "Sensitive Age".
In the scene where we see Tomoyo panicking as she attempts to put together an outfit for her upcoming “date” with Andou she begins to worry that Andou may dress up in cosplay when they meet. This is followed by a brief screenshot of Andou dressed up as numerous characters from different anime and shows.
While some are unidentified at this moment, the current character references are Hiei from Yu Yu Hakasho (left) and Kohtaro Minami from Kamen Rider Black (bottom-center)