things backwards and finding the first star in the sky. His 80 minutes of memory eventually begins to fail, and thus he is moved to a nursing home where he spends the rest of his remaining days. But the Housekeeper, her son Root, and his sister-in-law continue to visit him. While the Housekeeper is working for him, he teaches her and Root about many of the math skills he knows and loves. The Narrator/Housekeeper The Professor's housekeeper and a single mother. She was hired by the Professor's sister-in-law through the housekeeping agency and is the tenth housekeeper the Professor has gone through. She initially feels frustration at the Professor, who shows interest only in mathematics, but through observing the Professor's kindness and his passion for mathematics, comes to feel respect and affection for him. She first manages to connect with the Professor when he discovers that her birthday is February 20 (220), which is an amicable number with the number 284, which is imprinted on the underside of his watch, which he received as the University President's Award for a thesis he wrote in university on transcendental number theory. She cannot pronounce the title of the Journal of Mathematics (to which the Professor submits contest entries) very well, so she refers to it as "Jaanaru obu." Towards the end of the novel and at a pivotal point in the story, she and Root give the Professor a rare baseball card of Yutaka Enatsu as a congratulatory present. Root Ten years old. The Housekeeper's son. The Professor refers to him as "Root" on account of the top of his head being flat like a square root () symbol. He is the only character given something close to a name. He is an avid fan of baseball as well as the Hanshin Tigers just like the Professor, and gets the Professor to repair his old radio so that they can listen to baseball broadcasts together. His relationship with the Professor is close to that of a father and son, for the Professor is the first fatherly figure in his life. He eventually grows up to become a junior high school mathematics teacher. The Widow/Sister-in-Law Sister-in-law of the Professor (wife of the Professor's brother). Initially, she fired the Housekeeper for disregarding the employment contract rules (bringing her child into a client's home, staying past her assigned hours) and accused the Housekeeper's affection as