Mei Kinosaki is the deuteragonist of the story and a central figure in the protagonist’s unusual quest. Initially introduced as a target for assassination, Mei is a master marriage swindler of considerable reputation, claiming the ability to make almost anyone fall in love within thirty seconds, regardless of whether the target is a man or a woman. A crucial aspect of Mei’s identity is that, despite a feminine appearance that leads most people, including the assassin Hikaru Gero, to assume otherwise, Mei is actually a man. This ambiguity is a deliberate and professional choice, as Mei dresses according to the gender that will best appeal to a given target.

Mei’s personality is a blend of sharp pragmatism and surprising warmth. Having survived by manipulating emotions and expectations, Mei possesses a cynical and realistic view of romance, yet this is balanced by a genuine flair for the dramatic and a mischievous sense of humor. Beneath the confident and witty exterior lies a practical individual who is not afraid to speak frankly. Mei is also marked by a hearty appetite, enjoying delicious food despite a refined and elegant bearing. The primary motivation for entering the dangerous world of marriage swindling is revealed to be deeply personal: Mei needed to acquire a large sum of money to pay for the medical treatment of a sick younger brother.

In the story, Mei’s role is twofold. On the surface, Mei becomes Hikaru Gero’s personal marriage advisor and coach, using expert knowledge of romance and social dynamics to guide the socially inept assassin through the unfamiliar world of dating. This involves everything from giving relationship advice and arranging practice dates to coaching Gero on how to present himself. However, Mei is far more than a passive instructor. Actively accompanying Gero on his dangerous missions, Mei provides crucial on-the-spot social coaching and helps smooth over awkward situations, effectively becoming an indispensable partner in the field.

The key relationship is, of course, with Hikaru Gero. Their partnership begins unconventionally when Gero, instead of killing Mei, impulsively proposes marriage. Though Mei refuses this specific offer, a deal is struck: Mei will help Gero find a bride in exchange for Gero’s protection and financial support for Mei’s brother. Their dynamic evolves from a tense hostage situation into a genuine, if often chaotic, partnership. While Gero provides the brawn and lethal skill, Mei provides the brains for social situations, and a mutual respect and deep bond of trust slowly develop between them. The relationship is marked by bickering, teasing, and surprising moments of sincere support as they learn to rely on each other.

In terms of development, Mei begins as a cynical con artist solely focused on a personal goal, viewing relationships as a transactional game to be won. Through the alliance with Gero, who is disarmingly earnest and wants a genuine connection, Mei is gradually exposed to a different way of relating to people. While not undergoing a complete personality overhaul, Mei’s protective instincts and capacity for loyalty become more apparent, moving from a self-serving advisor to a dedicated partner who is invested in Gero’s success and happiness.

Mei’s notable abilities are almost entirely social and psychological. As a master swindler, Mei possesses an extraordinary talent for reading people, understanding their desires, and presenting a charming and trustworthy facade. This expertise in manipulation is repurposed as a legitimate tool to help Gero, allowing Mei to analyze romantic prospects, defuse tense social encounters, and devise strategies for Gero to showcase his own hidden charms. Mei’s true strength lies not in physical combat, but in the art of persuasion and the ability to orchestrate social outcomes with precision.