Neck hair-thread tourniquet syndrome (NHTTS) is a rare condition that can be a pediatric emergency, occurring when a hair or thread becomes tightly wrapped around a body part, leading to vascular or tissue damage. NHTTS commonly affects infants and young children and can result in severe complications if not promptly diagnosed and treated. The unusual nature of this event, the diffuse petechial hemorrhage on the face, and the presentation of ligature marks extending around the neck led us to admit the child to the general pediatric ward for follow-up and further investigation of the possibility of non-accidental trauma.Co-sleeping is a common cultural practice in Japan where parents sleep in close proximity to their infants. This case report aims to raise awareness among pediatricians and parents about the possibility of NHTTS occurring in infants who co-sleep, particularly when a strand of hair becomes entangled around their neck, about the early detection and appropriate management of NHTTS. And we also summarize the reported NHTTS cases.