As a Labrador puppy, Quill is sent to live with a couple, Isamu and Mitsuko Nii, who work as volunteers, training guide dogs (seeing eye dogs). When he grows to an adult dog, he is taken to a guide dog school, by a friendly, yet firm trainer Satoru Tawada. Although Quill is a little slower than the other dogs at the school, he seems to have an unusual 'empathy' and remarkable patience with his trainers. Tawade decides that Quill would be the ideal guide dog for Mitsuru Watanabe, but Wanatabe, a lonely and ill-tempered middle aged man, isn't as enthusiastic - he would "would rather sleep than be dragged around by a dog.". From here, the story is narrated by Wanatabe's daughter, Mitsuko, and slowly, Wantanbe is rehabilitated, venturing into the outside world, and learning, not only to trust other humans, but the animal at his side who guides him.