"Sumomomo Momomo - Chijō Saikyō no Yome" centers on Kōshi Inuzuka, a high school student who aspires to become a lawyer, distancing himself from his family's martial arts legacy. His life takes a dramatic turn when Momoko Kuzuryū, a girl raised in the mountains and trained as a martial artist, arrives to fulfill a centuries-old pact between their families. According to the agreement, Momoko is destined to marry Kōshi and bear a child who will inherit the combined strength of their bloodlines, ensuring the continuation of their martial arts heritage.

Momoko is exceptionally skilled in combat, possessing superhuman strength and agility, but her sheltered upbringing leaves her naive about modern society. Her arrival disrupts Kōshi's peaceful life, as she insists on living with him and protecting him from rival martial arts families who seek to challenge their union. Despite his initial reluctance, Kōshi gradually accepts Momoko's presence, though he remains conflicted about abandoning his dream of a normal life.

The series explores the dynamics between Kōshi and Momoko as they navigate their unconventional relationship. Momoko's unwavering dedication to Kōshi and her childlike innocence often lead to comedic situations, while Kōshi struggles to reconcile his feelings for her with his desire for independence. Supporting characters, such as Kōshi's childhood friend Sanae Nakajima, add further complexity to the story. Sanae harbors feelings for Kōshi and becomes a rival to Momoko, creating a love triangle that fuels both humor and tension.

Throughout the series, the narrative delves into the history of the Inuzuka and Kuzuryū families, revealing the weight of their martial arts legacy and the expectations placed on Kōshi and Momoko. The story balances comedic elements with action-packed martial arts battles, as the protagonists face off against various adversaries who test their skills and resolve. Themes of duty, love, and self-discovery are interwoven as Kōshi and Momoko grow closer, challenging societal norms and their own preconceptions about their futures.