In Episode 7 of "Nanatsu no Maken ga Shihai suru," the episode begins with a discussion about Darius, who has been missing for four months. It is agreed that he is likely dead, but the circumstances of his disappearance remain a mystery. The conversation takes a turn when Theodore McFarlane, a mysterious figure, interrupts the discussion. He sternly warns those present not to make an enemy of him.

Later, Pete notices a sudden change in his body that makes him uncomfortable. His friends notice his strange behavior, and when they confront him about it, Pete asks to be left alone. During the day, the students participate in their first broom-riding class, where they are introduced to living brooms. Nanao, one of the students, manages to tame a particularly difficult broom, impressing her classmates.

Afterward, the students attend a magical techniques class where they are tasked with disarming magical traps. The stakes are high, as failing to disarm the traps in time could result in injuries. During the exercise, Pete and Oliver find themselves in a dangerous situation, but Guy intervenes with a unique spell to neutralize the threat.

Oliver later confronts Pete about the changes he has noticed in him. He concludes that Pete has become a "Reversi," a rare individual who can switch between two genders. This revelation is confirmed when Pete displays new magical abilities. The upperclassman Whitrow overhears their conversation and invites Pete to a gathering for individuals with gender-specific magical traits.

At the gathering, Pete and Oliver meet various people who possess unique magical traits related to their gender. The atmosphere is welcoming, and the attendees are treated to a magical performance. Pete confides in Oliver about his feelings regarding his new identity and expresses his desire to continue sharing a room with him, albeit with some changes to maintain privacy.

The episode ends with the friends reuniting and sharing a cheerful moment over dessert.