The Kappa is typically depicted as a small, child-sized reptile-like humanoid with scaly skin, a beak, and a shell on its back, but its most crucial feature is a water-filled indentation (or "dish") on the top of its head. This dish is the source of its immense strength and is the key to defeating it—if the water spills out, the Kappa loses its power and becomes helpless.

The episode examines the dual nature of the Kappa:

1. The Mischievous Menace: Kappas are known for their love of pranks, ranging from harmless mischief to actively dragging people and animals into the water to drown them. They are famous for their favorite snack: cucumbers.

2. The Polite and Helpful Entity: Despite their dangerous side, Kappas are also deeply governed by Japanese etiquette. If you encounter one, the most effective defense is to bow deeply. The polite Kappa will feel compelled to return the bow, causing the water in its head-dish to spill, rendering it harmless. Kappas are also known to share medical knowledge with humans if treated with respect.

The episode concludes by discussing the likely origin of the myth, which may stem from early encounters with powerful river currents, water snakes, or large salamanders, serving as a memorable warning to children about the dangers of playing near water.