Saegusa-san presents herself as a cool, solitary figure at school, but this exterior hides a deeply asocial and insecure young woman who struggles to connect with others. The truth is that she is secretly in a relationship with an older male student everyone calls Glasses-senpai. The manga follows Saegusa as she desperately tries to bridge the emotional and physical gap between them, often putting herself in embarrassing or risqué situations in her awkward attempts to become closer to him. Her boyfriend, a serious and level-headed senior, is simultaneously tormented by her unintentional sex appeal, as he is just as inexperienced in romance as she is.

The narrative explores the daily struggles of these two first-time lovers who have no clear idea of how far their relationship should progress. The story is set in a modern high school environment, typical for a shonen romance, and focuses on their private interactions as they navigate the uncharted territory of dating. Key narrative arcs revolve around Saegusa's well-meaning but often misguided attempts to be a good girlfriend, which frequently backfire and leave her flustered senpai struggling to maintain his composure. Another notable recurring theme is their mutual attempt to set boundaries for their physical intimacy, a challenge made more difficult by their strong attraction to each other and their complete lack of prior relationship experience.