This special episode, which features only Adachi and Kurosawa, does not advance the story any further, but it is a nice addition to the series. If you like the series, this episode is a good addition to it, especially if you watch it immediately after watching the series. There's actually more humor in this episode than in the main series as we see Adachi and Kurosawa's colleague trying to find out why they are so close and draws and unexpected conclusion. I also like it that there's an indirect reference to Adachi's mind-reading power (which he has lost) as he now can't read Kurosawa's mind and find out what he likes but he is still slowly learning to understand Kurosawa better.