"Saru to Kani no Gassen" is a short anime series that adapts a classic Japanese folktale, often referred to as "The Quarrel of the Monkey and the Crab." The narrative centers on a conflict between a cunning monkey and a determined crab, exploring themes of trickery, revenge, and justice. The story begins when the crab finds a rice ball, which the monkey offers to trade for a persimmon seed. The crab agrees, plants the seed, and nurtures the tree until it bears fruit. However, when the persimmon tree produces fruit, the monkey refuses to share, climbing the tree to eat the ripe persimmons while throwing unripe ones at the crab.

The crab, injured and angered by the monkey's betrayal, seeks help from allies, including a mortar, a bee, and an egg. Together, they devise a plan to teach the monkey a lesson. The allies execute their strategy when the monkey returns to the crab's home, leading to a series of retaliatory actions that escalate the conflict. The mortar, bee, and egg each play a role in punishing the monkey for his greed and deceit, ultimately restoring a sense of justice.

The main characters include the crab, who represents perseverance and resourcefulness, and the monkey, who embodies cunning and selfishness. The supporting characters—the mortar, bee, and egg—serve as instruments of retribution, each contributing uniquely to the crab's plan. The story is straightforward and moralistic, emphasizing the consequences of one's actions and the importance of cooperation in overcoming adversity. The anime retains the simplicity and moral undertones of the original folktale, presenting it in a visually engaging format suitable for a younger audience while maintaining its cultural significance.