A woman was arrested Sunday morning on suspicion of stabbing her two preschool-age boys to death here the previous day, police said.
The 35-year-old woman, whose name is being withheld, said she killed her children "on impulse" and blamed a nervous breakdown caused by the stress of child rearing, police officials said. She had initially denied her involvement, they said.
Investigators at the Chiba Kita police station are trying to determine whether the woman, who has given incoherent responses during questioning, can be held criminally responsible, they said.
Responding to a call from the boys' father around 5 p.m. Saturday, the police found the brothers, aged 6 and 4, dead on blankets in their room with multiple stab wounds all over their bodies.
The mother had minor injuries to her hands and legs.
A knife with a 17-cm-long blade was found in the children's room. It had been taken from the kitchen.
The mother initially told her husband that a stranger broke into the house and stabbed the children.
Police suspect the mother of being involved because she had bloodstains on her clothes and there were no traces of another person breaking into the house,
The 38-year-old father of the boys has told police that he was watching TV in another room while wearing headphones and had heard nothing, according to the officials.
The couple also has an 8-year-old daughter, who was not home at the time of the slayings.
The house is in a residential area about 2 km northeast of JR Inage Station.