A 23-year-old part-time worker was arrested Friday on the technical charge of abandoning her baby's corpse, while her father was arrested on suspicion of burning the body in a park in the city of Fukui, police said.
Both Momoko Miyanaga and her father, Yoshihiro, a 51-year-old textile company executive, have owned up to the allegations, the police said.
Bones believed to be from the baby were seized at their home in the city, according to the police.
Investigators are questioning the suspects and family members they were living with to determine the cause of the baby's death.
Miyanaga is believed to have given birth to the baby in her room at their dwelling around November 2010 and to have kept the body after it died, the police said.
Yoshihiro burned the body after being told by his daughter in late December that she had been keeping it in her room, the police said.
Smuggler gets 16 years
The Yokohama District Court on Thursday gave a man 16 years in prison and an ¥8 million fine for smuggling ¥5.1 billion in drugs into Japan.
Presiding Judge Yasuhiro Kuga said Joji Honda, 62, tried to smuggle a large amount of stimulant drugs into Japan in a shrewd manner and described the act as "very vicious."
Honda, an automobile dealer, was involved in transporting roughly 64 kg of illegal stimulants dissolved in water in the gas tanks of two used cars shipped from Dubai to Yokohama port last May.
Kuga said the defendant was actively involved in the smuggling and expected a huge payment from Iranian traffickers in return.
Police arrested Honda and three other men last June at Yokohama port when they attempted to smuggle stimulants in a similar manner.