Potato is a supporting character in the anime Air. He is a small white puppy of unknown breed who lives as a stray in the town where the story takes place. Although he is generally regarded as a dog, he is something of a mysterious creature: he appears to understand human speech, and instead of barking he makes an unusual vocalization, the single word "piko." He is almost always seen in the company of Kano Kirishima, though he is not formally her pet and remains a stray.

Potato's background is tied closely to the meeting between Kano and the protagonist, Yukito Kunisaki. When Yukito first arrives in town, Potato steals his puppet, and this incident is what brings Yukito into contact with Kano. Earlier in the same sequence of events, Yukito performs a puppet show outside the local clinic, and Potato is the only one who stops to watch. This draws the attention of Hijiri Kirishima, Kano's older sister, who offers Yukito work doing odd jobs. Potato is also helpful in finding Kano on occasions when she wanders off while in a distracted or dazed state.

In terms of personality, Potato is curious, friendly, and playful. He is fascinated by Yukito's puppet and shows an attentive interest that other characters do not. He is also cooperative in an unforced way, following instructions given to him by Yukito, such as staying hidden in a bush for two days. His strongest attachment is to Kano, and he remains near her throughout her story, acting as a constant companion. His habit of saying "piko" instead of barking gives him a distinctive presence, and he largely functions as comic relief within the narrative.

Potato's motivations are simple and rooted in his nature as an animal. He is drawn to Kano's company and to Yukito's puppet, which he finds intriguing. His actions are driven by curiosity, affection, and a habit of staying close to the people he has bonded with, rather than by any larger purpose or goal.

In the story, Potato serves several practical functions. He is the catalyst for the meeting between Kano and Yukito, as his theft of the puppet brings the two characters together. His presence also connects Yukito to the clinic run by Kano's sister, leading to Yukito being hired for odd jobs. Beyond that, he provides comic relief through his unusual behavior, while also supporting the emotional tone of Kano's storyline by remaining a gentle and loyal presence at her side. In the film adaptation of Air, his role is greatly reduced, and he appears only in a brief cameo.

Potato's key relationship is with Kano Kirishima. The two are nearly inseparable, and Potato is widely considered her closest companion, even though he is a stray. His relationship with Yukito is also significant, as he is deeply interested in Yukito's puppet and cooperates with him when asked. Through this connection, he comes into contact with other characters, including Hijiri.

Potato does not undergo meaningful development over the course of the series. He remains the same stray dog with the same habits and personality from his introduction to the end. His role is consistent rather than changing; he exists to support Kano's arc and to serve as a bridge between Kano and Yukito.

Potato's notable traits include his distinctive "piko" vocalization, which replaces a normal bark and is unique to him. He is also noted for a strong homing instinct and a remarkable vitality, and he demonstrates an ability to understand and follow human instructions. These qualities, combined with his mysterious dog-like appearance, make him an unusual and memorable presence within the town.