The boy identified as C.Y.K. appeared in West Kowloon Magistrates’ Courts before judge Amy Chan Wai-man on Thursday. He earlier pleaded guilty to assault occasioning actual bodily harm, making and possessing child pornography, and blackmail.

Chan underlined the gravity of the boy’s crimes but noted his young age and sent him to a detention center as suggested by the probation officer.

The court heard that the classmate -- referred to as “X” -- borrowed the defendant’s phone but lost it in November 2020.

The defendant asked X to compensate him HK$4,800, and the duo met at the stairs on the 36/F of Hiu Kwai House in Kwai Chung Estate on December 4 that year.

However, the defendant found that X didn’t bring the sum of money he asked for and furiously pushed him down the stairs, beating him with slippers and signs.

He even had X take off all his clothes and instructed a 14-year-old girl accompanying him to take nude photos and videos of X, threatening X to repay him HK$9,000 or the photos and videos would go public.

In the early hours of the next day, the girl called X and told him to pay off his debts in three installments -- HK$3000 a week. X then informed his father of the incident and reported it to the police.

X was later admitted to a hospital for a thorough medical examination and was found to have sustained bruises to his ears and injuries to his right cheek, jaw, and limbs.

Under police caution, the defendant confessed that he was greatly enraged and lost control, committing the crime when X refused to repay him.