Hiroko Sasagawa, the gorgeous, vain and diabolical villainess known as Doronjo, is the leader of the deplorable Doronbo Gang. Aided by her hapless henchmen, Boyacky and Tonzura, she embarked on missions to locate and obtain the mysterious Skull Stones. It was later revealed that Doronjo was actually a lieutenant reporting to the criminal mastermind known as Dokurobei and that the Skull Stones were gems that could create a map to a massive cache of gold.
Despite her intellect and cunning, Doronjo is regularly bested by the young Yatter Riders. Eventually, Hiroko retired her role as a villainess to live a civilian life where she got married and started a family.
Actress Noriko Ohara provided the voice for the villainess; she first appeared in the premiere episode of the anime Yatterman airing on January 1st, 1977.