Police found the body of a child early Wednesday in a graveyard in Miyagi Prefecture.
They believe the corpse is that of a girl, identified only as Samia, who went missing 2 1/2 years ago at the age of 2.
Investigators found the body after the girl's parents confessed to burying it in a graveyard in the town of Hasama.
The confession came after the two were arrested in April on suspicion of neglect.
Police acted on information provided by staff at a local day-care center previously attended by the girl.
They arrested the parents, 44-year-old gang leader Yukio Suzuki and his 28-year-old Philippine wife, Benilda, on April 24 on suspicion of neglecting to feed Samia properly.
According to investigators, the child's mother stopped bringing her to the nursery in October 1999. The town did not report this information to police until March as Suzuki had told officials that Samia had been adopted by another couple.