Pop singer Kelvin Kwan Chor-yiu, who was arrested in Tokyo for alleged possession of cannabis, burst into tears on his weekend release after spending more than a month in detention.
Hong Kong Performing Artistes Guild president Alan Tam Wing-lun, who is Kwan's godfather, said Kwan, 25, called him immediately after his release from police custody.
"He couldn't stop crying over the phone. So I told him crying would not help and that what he did was something serious that deserves harsh punishment."
Tam said the young singer called him again the next morning but did not say much.
"It is no use apologizing to me. It is time for him to show his sincerity to the whole community and his fans," Tam said.
After being detained for more than a month, Kwan returned at about 8.30pm on Saturday.
Besieged by more than 100 journalists at the arrival hall, Kwan immediately made an apology and admitted he had "committed a big mistake."
His rumored girlfriend Wei Si, who is also known as Jill Vidal, remains in police custody in Tokyo.
The pair was arrested in Tokyo's trendy Shibuya district on February 24.
Kwan and Vidal are alleged to have been arguing with a shopkeeper in a 24-hour store when police were called.
Marijuana was allegedly found in a cigarette they were carrying.
In a Tokyo police interview, Canadian citizen Kwan, 25, had reportedly admitted the drug was given to him by a friend in Hong Kong.
British citizen Wei Si, 26, said she did not know it was marijuana.
But urine test results may have cast Wei Si's contention in a different light. Tokyo police have not made any further official announcement about charges.
Tam confirmed he had written a mitigation letter for Kwan. Kwan's parents also submitted letters.
"Their content is about Kelvin's background, his being a Hong Kong artist who is influential, his personal relationship with me and also about myself," Tam said. "I appealed [to Japanese authorities] for leniency but on condition that it would not affect their legal system.
"What I tried to do was simply to raise the concerns."
Tam said he does not know why Wei Si has not been released.