The Professor and his Beloved Equation
 The narrator's housekeeping agency dispatches her to the house of the Professor, a former mathematician who can remember new memories for only 80 minutes. She is more than a little frustrated to find that he loves only mathematics and shows no interest whatsoever in anything or anyone else. One day, upon learning that she has a 10-year-old son waiting home alone until late at night every day, the Professor flies into a rage and tells the narrator to have her son come to his home directly from school from that day on. The next day, her son comes and the Professor nicknames him "Root". From then on, their days begin to be filled with warmth.