Saki Watase, a hardworking but financially struggling office lady, accepts a lucrative part-time job as an XL condom reviewer to make ends meet. Her life takes an unexpected turn when her intimidating boss, Keisuke Sudou—known for his demon-like demeanor—escorts her home after a night of drinking and stumbles upon her stash of review items. Boldly declaring himself "XL," Sudou offers to help with the testing, sparking an intense physical and emotional connection between them. As their secret relationship deepens, complications arise with the arrival of charming rival Rik, a flirtatious XL guy who aggressively pursues Saki. Jealousy flares during office events, karaoke battles, and a tense hot springs trip, where Sudou's protective side shines through. Amid misunderstandings, overheard conversations, and aphrodisiac mishaps, Saki grapples with her insecurities and budding love. The series builds to emotional climaxes as both Sudou and Rik vie for her heart, leading to raw confessions and steamy resolutions. This erotic tale blends workplace drama, romance, and explicit XL action for fans of boss-subordinate fantasies and love triangles.