A light drizzle enveloped Hiroshi Yagi’s Toyota van as it hummed along a forest road near Lake Naguri in Saitama Prefecture. It was around 4 p.m. on Oct. 14, 1996, and Yagi was on his way back from scouting locations in which to set up equipment that could broadcast recorded wolf howls in the mountains to prompt real wolf howls in response.

He approached a particularly narrow stretch sandwiched between a steep cliff to the right and a valley leading down to a stream to the left. Yagi slowed the vehicle to a crawl, hoping he wouldn’t be trapped by an oncoming car. The one-year safety check on his automobile had expired and he couldn’t risk being caught speeding or having an accident.

As the path widened again, he noticed a four-legged animal making its way up from the creek.