"Cocoa no Kekkon Internet Marriage" centers on the unexpected union of two individuals brought together through an online marriage matching service. The protagonist, Cocoa, is a young woman navigating the challenges of adulthood and societal expectations. Seeking stability and companionship, she signs up for an internet marriage service, where she is matched with a man named Haruto. Haruto, a reserved and pragmatic individual, agrees to the arrangement for practical reasons, viewing marriage as a logical step rather than a romantic endeavor.

The narrative explores the dynamics of their relationship as they transition from strangers to partners. Cocoa and Haruto must navigate the complexities of living together, balancing their personal lives, and understanding each other’s quirks and motivations. The story delves into themes of communication, trust, and the evolving nature of relationships, as the couple gradually builds a connection despite their initial lack of emotional intimacy.

Supporting characters, such as friends and family members, play significant roles in shaping Cocoa and Haruto’s journey. These characters provide external perspectives and challenges, adding depth to the central relationship. The manga balances lighthearted moments with more serious reflections on modern relationships, societal pressures, and the concept of love in a digital age.

The plot progresses through a series of everyday scenarios, highlighting the couple’s growth as they learn to compromise, support each other, and confront their insecurities. The story avoids overly dramatic twists, instead focusing on the realistic and relatable aspects of building a life together. Through its grounded approach, "Cocoa no Kekkon Internet Marriage" offers a thoughtful exploration of marriage, partnership, and the ways in which people adapt to new circumstances.