The runner Shota thought he was going up against was a real guy. It’s a pretty sad story, actually. The bit with Shota sprinting past the (false) Tsuburaya is probably a reference to the conclusion of the Tokyo Olympics marathon.
Edit: I tried to link to this, but can’t get the url bbcode to work for some reason. https://en.wikipedia.org/wiki/Kōkichi_Tsuburaya