A Japanese man accused of causing the death of his 1-year-old son in 2018 by leaving him frail from severe malnutrition, refusing him medical treatment and shooting him multiple times with an air gun was sentenced to 16 years in prison on Thursday.

The Fukuoka District Court found Masanori Jokei, a 27-year-old man in Tagawa, Fukuoka Prefecture, guilty of causing injury to his son Yuiga and causing his death by abandoning his responsibility to him as his parent.

Photo taken in 2022 shows the Fukuoka District Court in southwestern Japan. (Kyodo)

According to the ruling, the defendant shot Yuiga with an air gun around late November 2018, causing injuries across his body that would have taken about three weeks to heal.

Jokei also conspired with his wife and the child's mother Ai to leave Yuiga heavily malnourished by around October of that year. The couple did not take him to a doctor the following month even though their son had broken bones, including his limbs, and an infectious respiratory disease, the ruling said.

Yuiga died aged one year and four months on Dec. 1, 2018, from acute respiratory failure.

"The agony and sadness the victim must have felt not only for the bodily pain inflicted on him but also for the lack of protection from his parents, on whom he should have been able to depend, is enormous," Presiding Judge Atsushi Tomita said in the ruling.

Jokei denied the charges during the trial's first hearing and remained silent throughout cross-examinations. His 16-year sentence matched the punishment sought by the prosecution.

An eight-year prison sentence for Yuiga's 27-year-old mother, who was convicted of causing his death by abandoning her responsibility to him, has already been finalized.

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