You're looking at the show's breathing room. These aren't bonus episodes bolted on for collectors; they're the cast when the apocalypse isn't actively ending, when Momiji can just be awkward around Daichi without a Natsume trying to kill everyone. The comedy hits because it trusts you've already bought into these people, so it can just watch them exist.
The Terrestrial Administration Bureau crew takes a break from saving Japan from ancient plant monsters. Between their dangerous missions, these specials capture the cast in moments of pure chaos: mundane tasks spiraling into absurdity, training sessions that go hilariously wrong, and the constant friction between personalities when supernatural threats aren't bearing down on them. Moments of slapstick comedy mix with character-driven humor that only lands if you know who these people are and what they actually do when the world isn't ending. The tone shifts dramatically from the main series, stripping away tension to let the ensemble breathe. You get Kusanagi's deadpan exasperation, Momiji's genuine earnestness creating disasters, and the team's collective dysfunction playing out in everyday scenarios. These aren't essential to understanding the larger story, but they reveal sides of the characters you won't see during critical battles. Perfect for viewers who got attached to the cast and want more time with them, even if nothing particularly important happens. Comedy works best when you care about who's being ridiculous.