If you see Roland Kong Kwok-fung throwing punches, don't worry. For the former secondary school teacher is merely giving classes in the Chinese martial art, wing chun, in English - hoping that he can help his students perfect both skills.
Kong started training in the form of self-defence with master Leung Sheng - the first Hong Kong disciple of legendary martial artist Yip Man - after being introduced by a Form Seven classmate.
'My friend learned only for a few months,' Kong says. 'But I learned for nine years.'
Kong used to practise about 10hours a week during those nine years, delicately balancing his love of wing chun with his teaching while also studying for a postgraduate degree.
Although Leung's school was disbanded after his death, in 1978, Kong continued practising and teaching wing chun as an extra-curricular activity.
He moved to Australia in 1994, where he opened an ice cream shop and taught the martial art in community centres. When Kong returned to Hong Kong in 1999, he taught English at secondary schools, then retired in 2005 and moved back to Australia to teach wing chun.
When he came back to Hong Kong six months ago, he thought: 'Why not teach it for free?'