Reiko Kuki works under the Accounting Department of a midsize toymaker and lives delicately due to a past event. One day, she meets Keita Saruwatari, the son of the toymaker's President who was furious about Keita spending too much money without thoughts and decided to send him to the Account Department to learn about money. Reiko later gets appointed as Keita's instructor to teach him the importance of money. Keita then moves in to Reiko's house as she begins her special summer training for him.
