Seventeen-year-old Sakata has lost everything. His mother is dead from a long illness, his father has abandoned the family, and he works nights at a construction site just to afford a proper funeral for his mother while falling behind in school. On the verge of giving up entirely, he is approached by a young man named Nishikawa, who makes a startling proposition: I would like to buy your time for two hundred thousand yen a month.

The deal comes with specific conditions. Sakata must attend school every day, gain admission to the same university as Nishikawa, and act as his friend for the duration of their five-year contract. Desperate and with little left to lose, Sakata accepts. The money allows him to bury his mother and escape the crushing weight of debt, but the arrangement is deeply unsettling. A friendship purchased outright, no matter how generous the terms, seems impossible to build on anything real. Yet as Sakata spends more time with Nishikawa, meeting his wealthy family and their servants who all vouch for his sincerity, the boundaries of their transaction begin to blur.

The story unfolds in a contemporary Japanese setting, following the two boys from the winter of Sakatas junior year through their shared plan to attend university together. The narrative divides into two distinct movements. The first half focuses on Nishikawa patiently drawing Sakata back from the edge of despair. Though Sakata never attempts suicide outright, he has clearly been planning his own end, and only through Nishikawas insistence and the unexpected support of his household does Sakata begin to find reasons to continue living. A secondary plot follows Sakatas school friend Toyota, who faces an abusive home life and must protect his younger sister, providing a contrast to Sakatas situation. While Sakata is pulled from darkness by an outsider, Toyota must fight his own battles without any savior.

The second half of the novel reveals why Nishikawa structured the contract around a five-year limit. His devotion to Sakata, his insistence on piano lessons he cannot avoid, and the quiet melancholy that surrounds him all point toward a tragic truth. Nishikawa has his own expiration date, and the friendship he purchased was never about money but about leaving someone behind who would choose to live. As the five years progress, the question at the heart of their relationship shifts from whether money can buy friendship to whether love can survive when time itself is borrowed. The novel is complete in a single volume, offering a self-contained story about two boys starved for genuine connection, the weight of grief, and what it means to move forward after loss.