P-ko is a supporting character in Arakawa Under the Bridge, a 22-year-old young woman with short red hair and red eyes who lives among the eccentric community that has settled beneath the bridge over the Arakawa River. She stands about 130 centimeters tall, and her listed personal details place her as a Pisces with blood type B. Her most distinctive visual trait is a pair of leaf-like strands of hair, and if she goes more than about five days without cutting it, a third shoot grows from the middle; if it is left alone long enough, it will eventually bloom like a flower. For this reason she regularly visits the Last Samurai to have her hair trimmed.

Her main role within the riverside community is that of a farmer. She grows vegetables, and in some descriptions fruit, for all of the residents, effectively providing the food supply for the village. During the winter months she leaves the bridge to travel in search of seeds and seedlings so that she can continue planting, and her stated motivation for wanting to earn a driver's license is to be able to travel further during those winter seed-gathering trips. Kou Ichinomiya, the protagonist who lives in the community under the name Rec, is strongly opposed to this plan, and during their argument over it he learns to his horror that she already possesses a motorcycle license.

In personality, P-ko is presented as the image of a klutzy girl, with her clumsiness taken to a dangerous extreme; what should be a minor accident tends to escalate into a massive disaster whenever she is involved. Aside from this destructive clumsiness, however, she comes across as one of the more grounded and cooperative members of the community, with a caring and considerate nature. She also frequently acts as the straight man among the odd residents, reacting with exasperation and pointing out the absurdity of their behavior. Her outward appearance is comparatively normal next to residents who wear elaborate costumes, to the point that Rec initially assumes she cannot actually be a resident of the riverside.

Her most important relationship is her close friendship with Nino, another resident of the bridge; the two are described as great friends who often talk together about love and romance. P-ko also harbors a crush on the Village Chief, and she grows cucumbers in her garden specifically for him. According to the things she herself says about her background, her father is described as someone who achieved love across species differences, while her mother is always in the field. Beyond that, the series does not give her an elaborate personal backstory, and she functions mainly as a steady, recurring presence who supports the rest of the cast.

In terms of development, she does not undergo a major dramatic transformation over the course of the story. Her character remains largely defined by her consistent role as the community's farmer, by her hopeless clumsiness, and by small recurring storylines such as her desire to get her driver's license and her attempts to express her feelings for the Village Chief. Her notable abilities are practical rather than combat-oriented: she is the village's reliable source of homegrown produce, and her peculiar hair growth is a recurring comedic trait. Her extreme clumsiness is the other trait most associated with her, routinely turning ordinary situations into chaotic incidents despite her otherwise mild and helpful disposition.