The first of the two novellas in this volume, Rentaru sekai (Rent-a-World), is narrated by 28-year-old office worker Yūta, who attends a colleague’s wedding and falls in love at first sight with one of the bride’s friends. Later, they happen to run into each other on the street and he strikes up a conversation with her. The woman named Mei reveals that she had been hired to attend the wedding as a “rent-a-friend.” Wanting desperately to go out with her, Yūta hires her to accompany him as his girlfriend when visiting a senior colleague’s home. Mei declares that the senior colleague’s so-called wife and daughter are a “rent-a-family.” The story delves into the service industry that has sprung up in Tokyo to provide image-conscious clients with fake friends, spouses, and families in various social situations.
The title story traces the friendship between Yukiko and Kaoru from when the two girls are still elementary-school age in 2009 until they turn 24 in 2022. Yukiko sets her sights on becoming a pianist and composer from early on, and with that in mind goes from high school to a music major in college. She is determined to find a style of composition and performance that no one else can duplicate. Her friend Kaoru is a math nerd who marches to her own drummer. She refuses to attend classes that she considers meaningless, such as gym. Neither of the girls has any other friends to speak of, and their own friendship is based largely on a shared interest in the avant-garde rock band “Over.” Yukiko in particular is in thrall to Over’s piano player, Hikaru.
The two girls are in ninth grade when they have a chance to see Over perform live for the first time, and the experience leaves a lasting impression on them both. Yukiko redoubles her determination to compose music “only I can write, and only I can play”?an ideal expressed by Hikaru. Kaoru is so amazed by the projection-mapping technology used in the staging that she decides to become a computer programmer?a decision that ultimately leads to her winning the grand prize in the National Student Inventor Contest when she is in college. Her winning entry is a computer application she originally developed for Yukiko called Piano at Home. It listens to Piece A being performed and learns the idiosyncrasies of the pianist, then plays a rendition of Piece B to which those same idiosyncrasies have automatically been applied. With the invention drawing attention from a variety of different businesses, Kaoru launches a start-up company.
When Yukiko finishes college she ignores her parents’ advice to the contrary and pursues a professional music career, but she fails to win awards in any of the contests she enters and can only find low-paying gigs. Since over half the market is now flooded with releases by virtual musicians created with sound and voice-synthesis technology, the conventional business model in which flesh-and-blood musicians were paid for live performances or for releasing albums has largely collapsed.
As time goes by, the two women come to realize that they have grown far apart in their thinking. Kaoru finds meaning and fulfillment in developing new technologies that will turn the irrational, inefficient, and antiquated into things of the past, whereas Yukiko believes it is precisely the things we can’t do, know, or control that make each person unique. What emerges is an insightful tale of how two women who grew up together arrive at diametrically opposed views about work, love, and life.