Ishishi is one of the twin boar deuteragonists accompanying Zorori, a constant companion alongside his brother Noshishi. He is visually nearly identical to his twin, sporting brown fur, green shorts, and an orange vest, sometimes accessorized with a green scarf and blue umbrellas. The sole physical distinction is the absence of a mole on Ishishi's right cheek, present on Noshishi.

Personality-wise, Ishishi shares a fondness for sweet foods and readily engages in mischief or troublesome activities with Zorori and Noshishi, showing unwavering loyalty to their adventures. Background details for Ishishi are largely unexplored across the series, offering minimal information about his origins. An earlier media reference notes the twins collectively took an oath not to return to their village until becoming accomplished villains, a narrative point not revisited later.

Within the specific dinosaur egg narrative, Ishishi operates as part of the trio with Zorori and Noshishi. The group receives an invitation from a dinosaur mother to witness egg hatching. Arriving on the island, they experience a hospitable reception. When a typhoon displaces the eggs, Ishishi joins the collective effort to locate and return the eggs to safety alongside his companions, responding to the storm's distress.