It airs a week after the show already ended, and the first thing Asakura does is ask why they're still here. That's the whole joke, and if that lands for you, this is the best two minutes on the schedule. Ishida to Asakura runs on nothing but two guys and dialogue, the same recycled intro loaded with different nonsense each time, and it dares you to call that lazy instead of the point. Reviewers keep reaching for words like existential and post-modern, which sounds absurd until you're actually sitting there watching characters negotiate with the fact that their series is over and nobody told them. It is genuinely thin, deliberately repetitive, and half the people who click it bail before the punchline. The other half rewatch it and quote it at friends who will never understand.
Ishida and Asakura find themselves in an awkward spot: the show was supposed to wrap up, yet here they still are. Asakura wants to know why they are still around when the anime should have ended the week before. This single bonus episode aired on Tokyo MX one week after the twelfth episode, and it plays that leftover appearance for laughs. It is a short, self-aware comedy extra for fans of the pair.