Reiko Kuki is a 27-year-old accountant in a mid-sized toy company who chooses to live a simple and frugal existence, valuing cherished possessions more than money. Then she meets Keita Saruwatari, the boss’s profligate son, who’s been transferred to her department to learn about money management. Before she knows it, Keita has come to live with her and her mother in their old house in Kamakura for more “financial training.” Although the penny-pincher and the spendthrift are as different as day and night, their relationship blossoms into a summer romance.

Reiko is trying to help Keita mend his profligate ways, both at work and in his private life. But she finds that their personal values are completely incompatible. Meanwhile, Keita learns that his ex-girlfriend’s fiancé, Yamashika, has been put in charge of an important new project at Monkey Pass. Determined to one-up his rival, Keita organizes a tennis match that pits his ex-girlfriend and Yamashika against Reiko and Ken, the man Reiko has been in love with for the past fifteen years. But Keita’s meddling in Reiko’s private life lands him in hot water!

Reiko is in high spirits as she looks forward to her first date with Ken, the man she’s secretly been in love with for fifteen years. But in the meantime, her coworker Jun spots Ken in public with a small boy and he informs Keita that Ken must have a son. After much deliberation, Keita decides to tell Reiko the truth about Ken but he loses his nerve at the last minute. Reiko has a wonderful time on their date, but just when she thinks she’s at last found true happiness something completely unexpected happens!

A sudden kiss from Keita sends Reiko’s heart into turmoil and she passes a sleepless night. But Keita is also unsure of his own feelings. With everything around her changing so fast, Reiko embarks on a journey to try to break free from her past. Along the way she encounters numerous problems, but by the end she realizes how she truly feels about Keita. How will their love story end?