To the primary schoolboys, he was a friendly uncle who invited them to his nearby home to play computer games or watch television.
But behind his apparently kind facade lay a devious sex predator who was luring naive children into his lair.
Once they were inside, his true colours emerged as he made them perform sick acts that could scar them for the rest of their lives.
Lok Kwok, 59, used the primary school as his hunting ground for potential victims whom he would chat up and befriend at the void deck of his block.
Between October 2012 and February last year, Lok, then a logistics officer, sexually abused five boys, aged between seven and 11, from the school in the west.
Lok, who committed 27 offences, pleaded guilty to seven charges of committing indecent acts with minors under the Children and Young Persons Act and one charge under the Penal Code of sexually penetrating someone aged under 14 years.
The serial paedophile is expected to be sentenced on Nov 3 for the eight charges, with the remaining 19 taken into consideration.
Court documents revealed that between 2012 and last year, Lok began having recurrent sexually-arousing fantasies and urges towards young boys.
He met two brothers, who were then seven and 10, at his void deck in October 2012 and invited them to his flat to play computer games, watch television and use his massage chair.
He later asked the older boy if he could take pictures of him. When the boy agreed, Lok asked him to remove his T-shirt.
Lok then asked the boy to hug and kiss him while the younger brother took photographs of them.
He performed the same acts with the younger brother.
The photos were later recovered by the police. Lok admitted that they were for his sexual enjoyment and that he had rewarded the boys for agreeing to the indecent acts by buying them game cards costing about $3.