She would befriend the elderly men through a matchmaking agency, usually going for those who are childless and well-to-do.
A serial killer dubbed Japan's "black widow" received a death sentence Tuesday for the murders of her husband and two common-law partners, as well as the attempted murder of an acquaintance, between 2007 and 2013.
The high-profile case has gripped the country, where she has become known as the Black Widow, after the female spider which kills its mates after sex.
Chisako Kakehi, 70, had her lovers drink cyanide after telling them it was a health drink, prosecutors claimed.
Poison was found in the body of at least two men she was involved with, and police reportedly found traces of cyanide in rubbish at Kakchi's home.
When prosecutors asked her whether she killed her husband by poisoning him, she replied that there was "no mistake".
Kakehi's lawyers have filed an appeal, and if Kakehi's sentence is upheld, it could be a long time before her execution. She married or was associated with more than 10 men and inherited about 1 billion yen, though she eventually fell into debt following her attempts to speculate in stocks and futures trading.
Her first husband died in 1994 and the business later went bust, prompting her to take out massive loans.
First diagnosed with mild dementia in 2016, Kakehi said she had trouble remembering events shortly after her arrest.
"The cases were well prepared in advance".
Prosecutors sought capital punishment while her defense counsel pleaded not guilty to the crime due to a lack of physical evidence, also arguing that she can not be held responsible as she suffers from dementia.
"Even if I were executed tomorrow, I would die smiling", Kakehi said at the time.
Nakagawa said Kakehi "made light of human lives" as she repeatedly committed the killings, adding that she offered "almost no words of apology" and had not reflected on her crimes.
While sentencing the old woman, presiding judge Akiko Nakagawa said: "It was an extremely malicious and sneaky crime borne out of greed for money".