Sumomo and Kotoko on a mission to return forgotten panties is the exact kind of stupid-funny premise that knows exactly what it is. The special exists purely to watch two chibi androids cause maximum chaos for the simplest possible reason. It's disposable, it's ridiculous, it commits fully to the bit.
Sumomo and Kotoko have a mission: track down Chii before anyone discovers she's left home without her underwear. What starts as a simple errand turns into an increasingly absurd chase through the city, with the two persocom sidekicks navigating the gap between their digital logic and human social customs. They're determined, well-meaning, and completely oblivious to how ridiculous the whole situation looks to anyone watching them frantically pursue a girl with a missing essential piece of clothing. The special trades in rapid-fire comedy, playing up the contrast between Sumomo and Kotoko's cheerful earnestness and the inherent chaos of their task. Ecchi humor threads through every scene as they encounter various obstacles and obstacles of their own making. There's a lightness to the whole affair that never takes itself seriously for a second. The tone is pure comedic farce with romantic undertones that frame just how much these androids care about their human companion.