Kaoruko Yamada

Kaoruko is Renko's "assistant" and thus always at her side. She is relentlessly upbeat and often tries to smooth over Renko's temper by putting her outbursts into more tactful form; nevertheless, she receives a fair amount of abuse when her attitude conflicts with Renko's serious, aloof demeanor. Kaoruko also figures heavily in a variety of Renko's inventions, often as the brains of whatever device has been created for the occasion. (While it not stated outright at first, it becomes clear that Kaoruko herself is actually an android, which explains why she interfaces so easily with Renko's other inventions.)