Ai Yuki debuts in the series' first episode, "Operation 01: Curious Fruit," portrayed as an innocent, virginal young woman. Her background frames her as inexperienced yet driven by a deep curiosity to explore unfamiliar settings. Accompanied by friends at a club, she witnesses an exhibitionist couple immersed in an underground sado-masochistic world. Their behavior captivates Ai, igniting her innate inquisitiveness. Spellbound, she follows them outside, a pivotal choice that pulls her into a hidden subculture defined by bondage and intense sexual encounters.

This immersion proves transformative. Through experiences involving submission and rough sexual interactions, Ai undergoes a profound shift in self-perception and conduct. Instead of rejecting this new realm, she finds liberation within it. Her initial curiosity evolves into a full embrace of the lifestyle, transitioning her from naivety to active participation. Post-transformation, she forms a passionate relationship with a young man matching her newfound lack of inhibition. Their mutual attraction stems from shared openness to the subculture’s practices, culminating her journey into a world she first discovered by chance.