A 30-year-old woman in the city of Kitakyushu was arrested Wednesday on suspicion of fatally stabbing her 12-year-old son, police said.
According to police, Masayo Miyagami was arrested for attempted murder at her home in Wakamatsu Ward after rescue personnel received a call at around 6:30 a.m. that someone had been stabbed. Medics found Miyagami's son, Masahiro, stabbed with a knifelike object.
The boy was taken to a hospital but died soon afterward, leading to the warrant against the mother being upgraded to murder.
Investigators quoted Miyagami as saying she wanted to die along with her son and her parents, but she has so far refused to give any specific motive for her actions.
According to police, she stabbed her sleeping son several times in the neck and chest with a kitchen knife at around 6:15 a.m.
The pair shared the house with Miyagami's parents, who were in another room and were alerted by noises. When they went to see what was going on in the woman's room, they saw their wounded grandson, according to police.
The grandmother took the knife from the mother, while the grandfather called an ambulance. The child was already unconscious when the aid car arrived, police said.
According to investigators, Miyagami had been working nights since her divorce in 1994, leaving her son in the care of his grandparents.