For the fans of Ryō Asuka, here's something you may have not seen before because it's not from any of the Devilman manga, it's from Tetsu no Shōjō Jun / Iron Virgin Jun.
It's actually not the same Ryo Asuka as Devilman, even if he has the same name and design. Here it's like Tezuka's Star System, reusing designs so the fans of previous works have specific expectations and also a way to make them understand something quickly and easily.
For instance, he makes the protagonists go to a party where people dance, one could be reminded of the Sabbath from Devilman and therefore expect bad things to happen.
Akira Fudō also appears a bit later, not as Devilman for once, but he's introduced beating a bunch of people and a Devilman fan would obviously expect Akira to be strong. Jun, the protagonist, was seen as really strong throughout this one-shot, an easy and quick way to make the readers believe that there's a threat to her is to reuse Akira Fudō's name and design, which is exactly what happens here.
But in the end, those aren't the characters from Devilman.