In the Kashigawa district of Japan, Dr. Kenji Endo and his wife Sumiko prepare for a dinner at the Red Monkey Inn to celebrate the beginning of Kenji’s primate field study. As the couple gets ready, they discuss the yams of Kashigawa, which restaurants transform into rice. Kenji thinks to himself that he would usually talk more about primates with his wife, but he has found himself feeling less energetic lately, likely due to his arrhythmia or the associated medication. Fortunately, today he feels fine, and brings up how some of the primates have been known to peel yams and even wash them in streams. At dinner, Kenji and Dr. Ogawa discuss past studies where researchers showed primates their reflections in mirrors and some orangutans showed signs of self-recognition. They also discuss the recent resurgence of wartime cuisine in Japan, which makes Kenji laugh. At this sign of his heightened energy, he thinks that his irregular heartbeat has begun to regulate itself, and he becomes excited. When yam-rice arrives at the table, however, Kenji experiences sudden fatigue and is extremely disappointed. A few weeks pass, and Kenji and Dr. Ogawa discuss the similarities of human and primate DNA. Dr. Ogawa proposes that humans’ higher intelligence and self-awareness violate what nature had initially intended—an anomaly. Kenji regards a young monkey and thinks of his son. Kenji’s condition worsens as he develops pro-arrhythmia, and his discontentment grows. Sumiko’s worry about his health makes him feel frail, but he snaps out of his haze when Sumiko embarrassedly mentions that she wants to take a train ride and he realizes that she must have many desires she does not tell him about.