Chisako Kakehi, 70, has become notorious over accusations she dispatched a number of elderly men she was involved with, drawing comparisons with the spider that kills its mate after copulation.
Kakehi is on trial for the murders of three men -- including a husband -- and the attempted murder of another, all to allow her to collect on insurance policies.
Prosecutors suspect she used cyanide to rid herself of her lovers, amassing a reported one billion yen ($8.8 million) in payouts over 10 years.
Her trial began in late June, but this week she stunned the court by telling judges it was true she had murdered her fourth husband in 2013.
"I was waiting for the right timing as I wanted to kill him out of deep hatred," the Asahi newspaper quoted her as saying on Monday.
The Fuji television network quoted her as saying on Monday that the crime was just "an issue of money."
But on Wednesday, Kakehi appeared to step back from those statements.
"I don't remember (what I said)", she testified, according to the Mainichi daily.
Kakehi's lawyers have argued she is not guilty of murdering Isao Kakehi on the grounds of diminished responsibility.
Kyoto District Court said last year that medical examinations found that Kakehi had early-stage dementia but was fit to stand trial.
If convicted or murder she could face the death penalty.
Kakehi shrugged off the prospect on Monday, saying "I'd be happy to die if you give me a drug now," according to the Asahi.
Kakehi had relationships with many men, mostly elderly or ill, meeting some through dating agencies, where she reportedly stipulated that prospective partners should be wealthy and childless.
Prosecutors say the men perished at her hands after making her the beneficiary of life assurance policies that ran into millions of dollars.
Reports say she subsequently lost much of the fortune through financial trading.
Japan's criminal justice system has come under scrutiny in the wake of Kakehi's arrest, with questions being asked as to why a number of her lovers' deaths were not investigated as suspicious.
In several cases, autopsies were not carried out on their bodies -- something that could have found traces of the cyanide detectives now believe she used to kill them.
Kakehi, who is also known as "The Poison Lady", is said to have stashed some of the substance in a plant pot that she later threw out.
Cyanide was found in the body of at least one of the men she was involved with before her recent marriage.
Police who earlier raided her home in Kyoto found traces of cyanide in the rubbish, media said.
They also found paraphernalia for administering drugs and medical books at an apartment she kept south of Kyoto.
The final hearing in the murder case is to be held in October with the verdict expected to be handed down in November.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)