We can clearly see that it's a taxi on pages 13 and 14, we even see what is presumably the driver's left arm on page 13 sitting in the driver's seat. More than anything else in this chapter, I'm curious what the taxi driver thinks about all this. Do their passengers typically push another passenger out of a door with a twenty foot shove, and then transform into giant demons? Or are they freaking out and driving away as this happens? Are they waiting there for someone to pay the fare?
So naturally I decided to see if this was in the web novel, and it is, in fact, in the original. Unsurprisingly, the taxi driver is actually a nameless lesser oni that is just disguised as a human. And there were a number of lesser oni that he all teleported into the air along with the ushioni, I guess the artist just didn't feel like drawing them or wasn't told to add them? This still leaves us with one question, which is, where did the taxi itself come from?