It was around 3 p.m. on a chilly day in December. The sky was overcast and the scent of rain hung in the air when Rina Kambayashi happened upon a creature she had never seen before.

Opening the front door to her family's gracefully weathered 150-year-old traditional wooden house, Kambayashi stepped out into the garden. She froze when she noticed a lone, dog-like animal standing among the withered shrubs growing by the rim of a small, empty, man-made pond. The distance between them was around 3 to 4 meters, the 53-year-old homemaker recalls when we meet in April at her residence on the outskirts of Chichibu, a mountain-ringed city in Saitama Prefecture.

Kambayashi says the animal stared at her for a few seconds before she called inside for her aging mother, Chiyo, to bring a camera. Her voice prompted the mysterious canine to disappear into the bamboo forest bordering a valley leading to the Anya River, a tributary of the Arakawa, one of the longest rivers in Japan.

The animal had an elongated, triangular snout. Unlike dogs, which typically have prominent foreheads, its face seemed relatively flat from the top of the skull to the nose, she recalls. It had a straight tail and patchy, black-and-brown fur. Around the size of a medium-sized dog, it looked hungry, with its ribs showing.