A middle-school boy lives with the black dog his divorced father left behind, and with it discovers an unidentified piece of flesh in the thicket of a park. As the dog, his classmate Sada, and his family become entangled, the boy's malice and unease rise with an almost tangible smell.

Around the flesh the dog digs up from the depths of the thicket, the boys' ordinary lives take on an unsettling outline.

Ririn moves to Tokyo from Hokkaido and begins his first job, where he becomes close to Sonu, a Korean resident of Japan. Having drifted through relationships without much reflection, Ririn encounters Sonu's questions of origin and identity, confronting both the invisible boundary between them and his own unawareness.

A coming-of-age novel that examines the invisible boundary between two close friends through their shared time.