"Who Wants to Marry a Billionaire?" centers on the life of a young woman named Aoi, who finds herself entangled in a high-stakes competition to win the heart of a wealthy and enigmatic billionaire, Kaito. Aoi, a hardworking and down-to-earth individual, is thrust into this unusual situation after being selected as one of several candidates vying for Kaito's hand in marriage. The selection process is orchestrated by Kaito's family, who seek to find a suitable partner for him through a series of challenges and tests designed to evaluate the candidates' character, intelligence, and compatibility.

The narrative explores the dynamics between the candidates as they navigate the pressures of the competition, revealing their motivations, insecurities, and personal histories. Aoi, initially reluctant to participate, gradually becomes more invested in the process, driven by a mix of curiosity, financial necessity, and a growing connection with Kaito. Kaito, on the other hand, is portrayed as a complex figure, torn between his family's expectations and his own desires. His aloof demeanor masks a deeper vulnerability, which becomes more apparent as the story progresses.

The manga delves into themes of love, ambition, and societal expectations, highlighting the contrast between genuine emotional connections and the transactional nature of the competition. As the candidates face increasingly difficult challenges, alliances and rivalries emerge, adding layers of tension and intrigue. Aoi's journey is marked by her determination to remain true to herself while navigating the complexities of the billionaire's world, leading to moments of self-discovery and personal growth.

Supporting characters, including Kaito's family members and the other candidates, play significant roles in shaping the narrative. Each character brings their own motivations and backstories, contributing to the overarching plot and the evolving relationships within the story. The manga balances moments of drama, romance, and introspection, creating a multifaceted exploration of its central premise. Through its engaging plot and well-developed characters, "Who Wants to Marry a Billionaire?" offers a compelling examination of love and ambition in the context of wealth and privilege.