NAGOYA--An overzealous father on trial here for stabbing his 12-year-old son to death while preparing him for an exam to attend a private school blamed the strict discipline that runs in his family.

According to court testimony, Kengo Satake, 51, struck him when the son behaved defiantly because he could not understand his schoolwork. The father was trying to get the child to obey him and help him study to be accepted to an elite private school.

Satake even tore his textbook and escalated his abuse by threatening the boy initially with a box cutter and later a kitchen knife.

“I realized that my son was afraid of this,” Satake said at a recent session at the Nagoya District Court, referring to a box cutter used to sharpen a pencil.

Satake, a resident of Nagoya, was recalling a winter day in 2015 when he was tutoring his son, who was an elementary school fifth-grader planning to take an exam to the school.

Even though the son had been rebellious at times, he immediately obeyed when Satake pointed the box cutter at him.

After that, the father turned to a more menacing object such as a paring knife and ultimately, a kitchen knife, to bring the son in line.

“My son behaved as I told him,” when threatened with a knife, he said.

“I didn’t need to yell at, or hit or become angry with him,” the father said.

Satake was charged with killing his son by stabbing him in the chest with a kitchen knife on Aug. 21, 2016. The child bled to death.

At the court hearing, prosecutors argued that the defendant controlled him through terror and violence while tutoring him.

His son’s death “resulted from his selfish act, which borders on abuse carried out in the name of education,” they said.

Prosecutors are seeking a 16-year prison term for the defendant.

But his lawyers argued that their client did not have the intent to kill his son and that the crime he committed was injury resulting in the death of the boy.

DEFENDANT AND HIS FATHER'S ALMA MATER

The incident occurred when the defendant was helping the son prepare for an exam to enter the exclusive junior high school that he and his own father had attended.

The son had expressed a desire to go to the school since he was very young. When he became a fifth-grader, the studying for the exam became more rigorous.

On the morning of Aug. 21, 2016, the son, then a sixth-grader, woke up after 7:30 a.m., later than he had promised.

Satake grew irritated as his son did not rush to finish breakfast quickly.

“All right, enough is enough,” the father yelled at him.

As the boy appeared to mutter something, Satake demanded to know what he had said.

“Nothing,” the pupil replied.

The father thought that his son was becoming defiant and grabbed a knife and scolded him.

Satake held the knife to his son’s chest while standing behind him as he attempted to ensure that the child would behave.

He did not want to hear the boy cry, so he covered his mouth with his left hand.

That was all the defendant remembers about the fatal incident.

As the father headed to the kitchen to clean his son’s saliva from his hand, he heard him say, “Daddy.”

“When I turned back to the direction the voice was coming from, I saw a human-like silhouette with something dark gushing from the chest,” he said in court.

HARSH DISCIPLINE RUNS IN FAMILY

The defendant’s father was a pharmacist. Satake's father's harsh discipline and being lectured about studying had been a part of his own life growing up.

Satake recalled being forced to give up playing baseball when he was in elementary school. His father told him he could take up the sport again after entering the junior high school.

Satake’s father verified in court that he had been strict in disciplining his son.

“I think I gave him rigorous discipline just as I had been given,” he said in a choking voice.

Satake’s wife said she was not allowed to have a say in “disciplining” of their son as Satake said she did not understand the need because she did not take an exam for a private school.

When her husband taught the boy in a room of their home, she was not allowed to enter.

She occasionally heard her husband shouting at the child, “You idiot!” in the room.

Although her husband denied it, she testified, “The defendant’s abuse of our son in the name of education was routine.”

Right before the incident occurred, the mother noticed that her son had a spot on his head where he had lost some hair.

When she asked the boy about it, he said his father had pulled it out.

The mother tried to talk her son into leaving with her soon to get away from his father, but he refused.

"I want Daddy and Mommy to be together, so I don't want to leave," the boy was quoted by the mother as saying. "Please wait until the end of August."

The family did enjoy some happy times. They took a trip. The father and the son ate chocolate and ice cream together.

But their relationship gradually deteriorated due to the pressure to get the boy into the school.

After the deadly incident, Satake even grew unsure about what the father and son were working so hard toward.

“Did my son really want to take an exam to enter the school?” he asked himself in his journal after being arrested.