He committed suicide by hanging himself on March 9, 2001, as a result of the Japanese Paleolithic hoax.
In 1962 he led an excavation at the Hijiridaki cave site (聖嶽洞窟遺跡) in Ōita Prefecture.
The team claimed that they discovered ancient human bones and stone tools dating back to the Paleolithic era, but later in 1999 other researchers questioned this conclusion and argued that the claim could not be proven.
[1] In a series of articles by the Japanese magazine Bungeishunjū published on January 25,[2] February 1 and March 15, 2001, it was alleged that the stone tools discovered at the site were fabrication and indicated Kagawa had been involved in that hoax.
On October 25, 2003, a project team from the Japanese Archaeological Association stated that they could not find any evidence to make judgments whether there was a fabrication or not.