Set against the backdrop of a global jalapeño and spicy food craze that has reshaped culinary landscapes from America to Japan, the story unfolds at a lively teppanyaki restaurant.

Twenty-three-year-old Reiko and her partner are enjoying a dinner out when Reiko spots a shocking sight half-hidden behind a decorative screen: thirty-year-old Masahiro, the boyfriend of the protagonist's sister Aiko, sharing an intimate dinner with twenty-five-year-old Sadako, who is Aiko's close friend.

Overhearing their conversation, Reiko and the protagonist discover a deep betrayal. Masahiro and Sadako have been carrying on a clandestine affair for months, meeting in hotels in Shinjuku, exchanging late-night messages, and sneering at Aiko as "too innocent and plain." Masahiro dismisses Aiko as a mere family obligation while feeding Sadako promises of passion and a future together, completely unaware they are being watched.

Filled with fierce loyalty and burning anger, Reiko grips the protagonist's hand, declaring that Masahiro's actions have disgraced the family name and tarnished their honor. Rather than rushing into a reckless confrontation where the cheating couple can weave excuses, Reiko stands firmly as an ally, urging a calm, calculated strategy. With the betrayal fully exposed, the stage is set for a carefully planned reckoning to dismantle the deceit and protect Aiko.