Naoki Murakami is the kind of student others envy. A third-year at Hakodate Koyo High School, he possesses a rare combination of sharp intelligence, good looks, and natural athleticism. His path seems clearly mapped out for success, with Tokyo University as the ultimate goal. That focus, however, shatters the moment his friend Sano drags him to watch a women's tennis club match. On the court, he sees Haruka Mizuno, and it is love at first sight.

Without hesitation, Naoki approaches her the very next day and asks her out. To his surprise, the intelligent and beautiful Haruka accepts, and a tender but intense romance begins. The two quickly become a couple, sharing the ordinary yet profound experiences of high school love. Yet, a dark cloud hangs over their happiness: the impending Tokyo University entrance examinations, one of the most grueling and competitive academic trials in the nation. They both know their relationship is on borrowed time, pressured by the countless hours of studying required for the exam.

The story follows Naoki and Haruka as they navigate this fragile balance between young love and academic ambition. Every date is shadowed by the guilt of not studying; every moment of happiness is a potential distraction from their future. The central narrative arc builds relentlessly toward the exam day, forcing them to confront an impossible question. What will happen to their relationship if only one of them passes? As the results draw near, the strain tests their devotion, revealing their deepest insecurities and the true strength of their bond. The drama unfolds against the backdrop of a typical Japanese high school and the pressure-cooker environment of cram schools, capturing the bittersweet reality of a first love that may have an expiration date.