Nia is the first setting to be shown in Kokiro. It is notable for being Kokiro's homeworld.
Nia is apparently very advanced in terms of technological progress. The scientific achievements of its inhabitants include several generations of sentient robots, as well as the world's first time machine. Weapons technology, such as guns and explosives, appears to be very similar to that of present-day Earth, but other items from the past, such as the car, are no longer in use. It is also noteworthy that no trees grow naturally on Nia, and they can only be seen "in museums". However, the inhabitants of Nia do have considerable, if not always accurate knowledge of even quite inconsequential details of the past.
It is currently unknown whether humans live on Nia; although Pippin appears to have been built after the model of a human figure, her taser does not have a setting marked "human". The non-robotic inhabitants encountered so far (Angellene, Sandy, and Sunny) all possess large, downward-pointing ears similar to those of the Jitai.