"King of Breasts" is a comedic and satirical anime series that revolves around the absurd and exaggerated premise of a world where breast size determines social hierarchy and power. The protagonist, Hiroshi Tanaka, is an ordinary high school student who unexpectedly gains the ability to manipulate and control the size of breasts after a bizarre encounter with a mysterious artifact. This newfound power thrusts him into a chaotic and surreal society where individuals with larger breasts hold significant influence and authority.

As Hiroshi navigates this peculiar world, he encounters a variety of characters, each representing different facets of the societal obsession with breast size. Among them is Rina Takahashi, a fiercely ambitious classmate who seeks to exploit Hiroshi's abilities to climb the social ladder. Another key figure is Yuki Nakamura, a shy and reserved girl who becomes Hiroshi's confidante and moral compass, often questioning the ethical implications of his powers. The series also features antagonists like the tyrannical "Breast King," a powerful figure who rules over the land with an iron fist, using his immense influence to maintain control over the population.

The plot unfolds through a series of episodic adventures, blending humor, satire, and occasional moments of introspection. Hiroshi's journey is marked by his struggle to balance the temptations of power with his own sense of morality. The narrative explores themes of societal pressure, self-worth, and the absurdity of superficial judgments, all while maintaining a lighthearted and often absurd tone. The series culminates in a climactic showdown between Hiroshi and the Breast King, where the true nature of power and influence is ultimately questioned and redefined.