The recent arrest of a man who allegedly hit his one-month-old daughter in the head leading to her death last year has highlighted the urgent need for better support and education for fathers, following a spate of similar cases across the country.
Paternal abuse in some cases has been attributed to a phenomenon known as "papa mishiri" in Japan, roughly translating to "daddy aversion."
While some experts interpret it as a sign that a baby's cognitive skills are developing, they acknowledge that inexperienced fathers may feel shocked when their children appear to reject them.
The 23-year-old man, Natsuki Nakashima, initially denied injuring his daughter Kokona at their home in Kanoya, Kagoshima Prefecture, but he later admitted to the allegations.
Nakashima was at home with Kokona and another of his four children when the incident occurred.
"Stress had been building," he said. "I hit her because she would not stop crying."
However, it is unknown whether Nakashima's case is linked to papa mishiri.
Masako Ishii, professor of developmental psychology at Showa Women's University in Tokyo, said babies with improved cognitive abilities are able to feel the difference between their mothers and fathers, and the subtle changes in how they hold them.
She said in families where mothers handle most of the child-rearing, it is common for infants between six and eight months old to reject their fathers for a period of time.
According to a survey by the Ministry of Health, Labor and Welfare, around half of the child abuse deaths in fiscal 2019 involved children less than a year old.
For some fathers unaware of how to handle this phenomenon, the situation can quickly deteriorate and have serious, even deadly, consequences.
In another case, Kazuki Takakura was sentenced to nine years in prison by the Mito District Court this year for manslaughter, after his 10-month-old daughter Hazuki died in Hitachinaka, Ibaraki Prefecture, northeast of Tokyo.
He cited the "stress due to her not warming (to him)" as one of the reasons for the physical assault that resulted in Hazuki's death.
"She cried just by looking at my face, it shocked me," Takakura said in an interview with Kyodo News at the Mito detention center. "I was anxious for her to let me hold her, but there was no one I could talk to about it."
Other incidents include a man in Chiba Prefecture, east of Tokyo, who was convicted of inflicting injuries on his four-month-old son in 2019.
"He cries every time my wife is not there," he said during questioning.
November is Child Abuse Prevention Month in Japan, which experts like Ishii say provides an opportunity for fathers to learn about child development and set up counseling services.
The cases of abuse have highlighted the need for greater support for both mothers, who are prone to conditions like postnatal depression, and inexperienced fathers.
In response, the ministry has started a subsidy program to encourage local governments to set up peer support groups that invite men with experience to talk about parenting, and is urging all municipalities to establish child-rearing support centers.
"When babies don't understand language, it's easy for parents to feel under pressure," Ishii said. "Especially, fathers do not go through pregnancy which serves as preparation (for parenting) and need more education and support."