TV-Series
Description
Pion is a supporting character from the anime Humanity Has Declined who appears during the story arc centered on the Summer Electric Festival. She is first introduced as a mysterious cat-eared girl whom the protagonist, Watashi, encounters at the festival. Pion is suffering from memory loss, referred to in the story as record loss, and because she cannot correctly remember her own name, Watashi gives her the nickname P-ko and also calls her Pion. In appearance, she is a teenage girl with short blue hair, purple eyes, and distinctive animal-like ears.

As the arc progresses, Pion's true nature is revealed. She is not an ordinary girl but a cat-like robot that has arrived on Earth, and her actual identity is the unmanned deep-space probe Pioneer, which has taken on a human form. Due to her damaged records, she spends much of her time unaware of what she really is, and her main concern is finding a fellow probe, a colleague referred to by names such as O-tarou, Oyage, or Voyager 2.

In terms of personality, Pion is cheerful, curious, and described as loving justice. Her behavior blends a straightforward, task-oriented outlook with an endearing mechanical habit: she emits small sound effects whenever she notices or acknowledges something that interests her. She is friendly and trusting toward Watashi, and her innocent, slightly bewildered manner makes her a sympathetic presence, even as her arrival introduces a more distinctly science-fiction element to the story.

Pion's motivations are closely tied to her amnesia. Her immediate goals are to recover her lost records and to reunite with her missing companion, and this search drives most of her actions during her time in the story. Once her identity as the Pioneer probe comes to light, her significance changes, as her existence is briefly regarded with great interest and seen as a potential turning point for humanity, though those expectations ultimately do not lead anywhere lasting.

Her notable abilities stem from her origin as an advanced space probe. In her humanoid form she can interact naturally with people while still displaying mechanical traits, such as her habit of producing sound effects, and as a machine she does not share the biological needs of ordinary humans. Her very existence also connects her to an older era of human space exploration, a level of technology that has long since faded from the declined civilization she finds herself in. Her development over the arc is essentially a journey of self-discovery, as the amnesiac catgirl gradually learns what she truly is and what her return to Earth means.