A 32-year-old woman of Sumoto, Hyogo Prefecture, was arrested Monday on suspicion of fatally abusing her 10-month old son, police said.
They said Kyoko Ishibitsu, a restaurant employee, has admitted to the allegations.
According to investigations, Ishibitsu brought her son, Kaito, to a prefectural hospital in the city at around 10 p.m. Sunday, saying he had suffered a convulsive fit. He died several hours later of a subdural hematoma.
The mother told hospital staff her son started shaking when she tried to put him to bed. The staff notified police, however, because they found evidence of traumatic bleeding.
Ishibitsu later told police she pushed the boy down because he would not stop crying. He fell and hit the back of his head on the floor, she was quoted as saying.