Ishishi serves as a deuteragonist alongside the fox Zorori, functioning as one half of a twin boar apprentice duo. He presents as a brown anthropomorphic boar typically dressed in green shorts and an orange vest, occasionally adding a green scarf and blue umbrellas. The sole physical distinction marking him from his identical twin brother, Noshishi, is the lack of a mole on his right cheek. As the elder twin, Ishishi possesses a deeper vocal pitch compared to Noshishi's higher-pitched voice.

Ishishi and Noshishi share nearly identical personalities, defined by their fondness for sweet foods and their tendency to engage in mischief under Zorori's lead. Both exhibit unwavering loyalty, accompanying Zorori on his varied adventures. Their background receives minimal exploration in official media, though the 1993 film adaptation features Noshishi mentioning an oath not to return to their village until becoming "real villains"; this narrative element remains isolated and unexplored elsewhere.

The twins debuted in the inaugural story *Kaiketsu Zorori: The Dragon Slayer*, discovered arguing over oden in a Levanna Kingdom alley. Noshishi demonstrates a specific skill in drawing, accurately reproducing a genie from memory in season 1 episode 8 of *Motto! Majime ni Fumajime Kaiketsu Zorori*; no comparable artistic ability is noted for Ishishi.

In the film *ZZ no Himitsu*, Ishishi and Noshishi journey with Zorori after his alarm clock unexpectedly acts as a time machine, transporting them to the past. There, they encounter Zorori's mother in her youth and the treasure hunter Zorondo Ron. They collaborate to retrieve their time machine from police and confront a kaiju threat. While Ishishi participates, the film provides no unique character development or specific actions solely attributable to him beyond his consistent role within the core trio.

The names Ishishi and Noshishi derive etymologically from the Japanese word "Inoshishi," meaning wild boar, split between the twins.