Sixteen-year-old Karton loves basketball. He loves singing. He does both well, but he says those two activities "are not getting on well" and force him to make hard decisions.
The Form 5 student of La Salle College is captain of the school basketball team. He is also the undisputed best singer in his school, famous for his beautiful voice and emotional expression.
He topped the Talent Quest singing contest at La Salle last year - and could have won more singing titles.
"I missed the finals in Form 3 and Form 5," Karton said. "I had an important basketball game on the final day of the Talent Quest two years ago, so in the end, I decided not to sing and played for the team."
He faced the same situation again this school year. He chose to take part in the A-grade basketball final against Ying Wa College instead of defending his singing title. Unfortunately, his team lost.
Last year, he worked his way into the 30-strong semi-finals at an annual inter-school singing contest called Supernova. Then he attended a Nike All-Hong Kong Youth Basketball League training camp - where he lost his voice - and had to give up the contest.
It was yet another case of a conflict of interests this year.
"I would have liked to join the [Supernova] competition again, but the semi-final [this year] fell on the day of my departure to Inner Mongolia for the All China Secondary Schools Students' Games", he said. He played on the Hong Kong team.
"So I didn't apply at all as I wanted to focus on the basketball competition."
His selection to that team came about because his determination in scoring had impressed the recruitment teacher. That was despite his 1.73-metre frame, which is shorter than the standard height of a shooting guard.
To Karton, the most important thing when he stands on a court or on a stage is to be able to enjoy his hobbies.
"That is why I won't feel sorry if I decide to go to any one of the two activities but end up losing the contest.
"But if I must compare, I would like to win a basketball trophy more than a singing award, especially an individual prize. That would prove my team is the best and I have done very well to help it."
Karton had a taste of such a prize at the Panasonic Inter-school Basketball Competition in May, where he was the top scorer.
Can he sing, play and study at the same time? Karton said he had found his own way of managing his time and emotions, inspired by Rainie Yang of Taiwan.
"What I have learned from Rainie's success is her real talent in excelling as a singer, actress and programme host," he said. "I know I can be like her, too."
The amateur vocalist says friends have told him he sings like Jason Chan Pak-yu, but he likes Jay Chou's songs more.
He admitted being keen to join show business, but felt he was not ready to take part in any televised contest yet.
"Singing makes me calm even when I have to compete under pressure in sport. It is also my dream to become a singer. But I don't want to join showbiz yet," he said.
"Besides, I still want to play top-level basketball and get a degree in pharmacy."
Facing the problem, Karton has found something more useful than a time-turner. He has a strong belief he can overcome the obstacles so that he can sing, play and study well for the Hong Kong Diploma of Secondary Education exams.
In any case, his ultimate target before school graduation is not singing-related. "As captain of the basketball team," Karton said, "I would like to win the HKSSF and Jing Ying inter-school tournament titles for my school this year."