But in five short years, the youngster who liked to bang on the family's $200 piano has progressed to dashing off sonatas and concertos with a technical skill and musical maturity belying her 11 years.
On Sunday, she will perform Mozart's Piano Concerto No 23 - a work she first learnt last year - with the Collegiate Community Orchestra.
The piece is more than 20 minutes long and she will play without a score.
It will be her first experience of performing with an orchestra, and Modi confessed yesterday to feeling "a bit nervous".
The Deng family emigrated to Dunedin from China when Modi was 2.
Her mother, Shuang, said Modi was attracted to the piano as a toddler, but would hit it with both hands at once, like most children do.
It was not until she began taking piano lessons when she was almost 6 that her abilities were recognised.
"We thank God for her talent - it doesn't come from us," Mrs Deng said.
She said she did not know anything about music, while Modi's father, Jeremiah, was a "music listener", but not a performer.
Modi passed the difficult grade 7 exam when she was 9 and for the past 18 months has been taught by Tom McGrath, a teaching fellow at the University of Otago.
Modi's talent was "quite rare" in one so young, he said, describing teaching her as "a pleasure and a privilege".
"She learns things very quickly, gets around the piano, and is very musical."
Mr McGrath said one of his most difficult tasks was selecting music for Modi to play, as her hands were still quite small.
"The wrong music can be potentially damaging for young hands.
"I have to be careful she doesn't play pieces which are too heavy for her yet. But her hands are growing quickly."
Modi said she practised about an hour a day on the new piano her parents bought for her.
Asked whether she would pursue a career in music, the Columba College year 7 pupil said she would probably continue to make music, but wanted to write.
"I want to be an author. I like English."
The Music for a Sunday Afternoon concert will be held in Marama Hall at the University of Otago at 2.30pm.
