The role of the boy was cast by searching in Tokyo children's homes, eventually finding the young orphan Tetsuo Abe. Abe's own life resembled the fractured childhood of the character he was to play, and he was allowed to join the production with the children's home's permission. After the film's release, Abe was put up for adoption but refused it and chose to stay at the children's home's. He would never act again.
The yellow cap Toshio wears sold in Japan for schoolchildren to wear so drivers could see them in traffic.
Based on real events in 1966.
Oshima wrote the script in 1966 after reading about the real criminal family. It wasn't until 1968 did a production company agree to fund the completed screenplay.