Keiko Ikawa, part of the Igawa family alongside her mother Yoshiko, brother Tsuyoshi, and younger sister Noriko, contrasts sharply with her domestically responsible brother through her academic excellence as a top-ranking student, which fuels her popularity. Her pale skin, long black hair extending past her arms, and conventionally attractive features draw romantic pursuit from Yoshihito Sagino, Tsukasa Watanabe, and Officer Jun.

Despite these advantages, Keiko exhibits significant personal flaws. She displays incompetence in household tasks like cooking, cleaning, and appliance operation, embodying a "Womanchild" archetype. Habitual alcohol consumption leads to frequent heavy intoxication, resulting in comical incidents like mistaking bus stops for her home. She openly declares her dislike for children but maintains public politeness toward them, and harbors a specific phobia of cats.

Keiko consistently mistreats her brother Tsuyoshi through physical abuse—slapping, ear-pulling, or knocking him down—while rarely acknowledging his efforts in handling her neglected chores, casting her as a "Big Brother Bully." Their mother Yoshiko favors Keiko and Noriko, neglecting Tsuyoshi.

In a time machine narrative, Tsuyoshi and Tsukasa Watanabe travel 12 years into the past, encountering younger versions of themselves and discovering the identity of Keiko’s first romantic interest. Her story concludes with marriage to Yoshihito Sagino, an academically accomplished Tokyo University graduate whose appearance contrasts with hers, fulfilling the "Ugly Guy, Hot Wife" trope in a "Happily Married" resolution.