Five Labrador Retriever dogs were born to a family in Japan. The woman to whom the dogs were born wants her dogs to be trained as guide dogs. The person whom she called said that they were looking for dogs based on heredity and that the mother of the dog concerned was too ordinary. After repeated pleas, the person agreed, but said that only one of the dogs would be accepted. To choose this dog, the woman was told to conduct a test whereby she placed the dog a distance away from her, and called for them. When she did so, four of the five dogs ran to her, leaving one dog, which had been "wondering what had happened". This dog was selected to be trained as a guide dog and was brought away from its family, constituting its first parting with its company.
The dog was sent to puppy walkers Isamu Nii and Mitsuko Nii, whose primary job was to raise the dog until its first birthday. Using an English-Japanese dictionary, the couple named the dog "Quill". Quill spent the time playing in the garden and with the babysitters. Soon, snow was seen in their garden, reminding the couple that the dog would have turned one soon. The day, they walked Quill for a longer time in the sakura trees. Soon, Quill was brought away in a van, constituting its second parting with its company.
Quill was then brought to the training school. Soon Quill's trainer Satoru Tawada familiarised Quill with the English terms "curb", "corner", etc. and could stop whenever it met one of these. It was also familiarised with "left go", "right go" and other terms during training. When the trainer sat the dog down, he apparently forgot about Quill and was walking another dog, when he discovered that Quill was still waiting. He remarks that waiting was one of the most important things in a guide dog.
During training, Quill was walked to a supermarket, and a middle-aged man Mitsuru Watanabe met Quill, and expressed that he would "rather sleep than be dragged around by a dog". In another afternoon, Tawada, with Quill, saw Watanabe walking to his office in his stick, and Tawada suggested that the trip would have taken only five minutes with a dog. Reluctantly, Watanabe walked Quill in his harness to his office with ten minutes to spare.
Slowly, Watanabe realised that a guide dog would have been useful. Watanabe was trained with Quill in the training centre to work with each other, and Watanabe was taught to use English since it was less confusing than Japanese, being familiarised with the terms "left go" and "right go". However, Watanabe fell in the final examination, having not listened properly to his dog about the obstacles around, and fails it. He soon learned to work with the dog more cohesively and earned his license certificate.
A shelter was built for Quill back at home; however, it was too small. It was rebuilt, but without a shelter. Watanabe left Quill in the rain, and Quill ran away. The next morning, Watanabe, who was alerted by the woman who offered to keep Quill for the night, retrieves Quill.
Watanabe continued to work with the guide dog and learned to trust him. However, Watanabe was stricken with diabetes and ended up in the hospital when the condition worsened. Quill was returned to the training center while waiting for Watanabe to recover. The wait took three years, when one afternoon, Watanabe came to the center and walks Quill for thirty metres, for the last time in his life. Watanabe went back to the hospital shortly and never recovered. Quill visits Watanabe's funeral, but seemed to "think that he was asleep" in his coffin, marking the third parting with his company.
Seven years passed and Quill never worked as a guide dog again. Throughout those years, he was a demonstrator guide dog in the training center. Eventually, he returned to the Nii family, seeming to have remembered everything that happened in the one year they spent together. One fateful day, Quill succumbed to old age and sustained several bone injuries when he fell trying to climb a step. That night, the couple shared with Quill that they knew it was painful for him. They watched over him throughout the night until he died at the age of 12 years and 25 days.