Speaking to state news agency Andina on Sunday, Nelly Calderon said she felt frustrated at Japan's failure to act so far.
"I think we should give up on direct extradition attempts and go to the court in The Hague ... we've given Japan enough time and it's time for it to decide," she said.
Fujimori fled to Japan, his ancestral homeland, at the height of a corruption scandal in 2000.
Peru has formally requested his extradition on charges of political responsibility for 25 murders by a death squad - for which prosecutors want the former president jailed for 30 years - as well as corruption charges.
Calderon said Japan apparently wanted to delay things so a statute of limitations would prevent Fujimori, Peru's president from 1990 to 2000, from facing trial.
Japan, which has said it is studying the extradition requests, does not as a rule extradite its nationals and the two countries have no extradition treaty.