His main musical love is composing, which he does into the late hours.
Nathanael has composed pieces for solo instruments, bands and whole orchestras in genres ranging from nocturnes to blues and bluegrass.
His interest was spurred when his parents took him to a live brass band at age 7.
"After that I told my parents I wanted to study music.''
After only a year and a half his theory and composition skills are at university level.
He learns clarinet on Tuesday, piano on Wednesday and cello on Saturday, with the aid of
music teachers Barry Rutledge and Eli Gray-Smith.
Gray-Smith said the boy's talent was "outstanding''.
"He is very good and has perfect pitch. In his exams he's always getting distinction.''
Nathanael is home-schooled at the family's house in Glenleith.
At the end of the year he will sit Cambridge exams in chemistry and mathematics which are equivalent to NCEA level 3 and provide university entrance.
He is pushing to go to university next year, but father Chris Koh imagines he may not be let in so young.
"But we have to let him try.''
Koh said his son was very self-driven.
"He actually wrote into the New Zealand School of Music asking for entry. He's very self-
motivated, but has also had a lot of help from Barry and Eli.''
Neither he nor his wife Wendy were musical, he said.
"I don't know where he gets the genes.''
The family are originally from Singapore, but now have New Zealand residency.
Nathanael was granted the Inaugural Ministry of Education gifted learner award in May.
This adds to his long list of skills and achievements including proficiency in written and spoken German, a membership to both the Singapore and New Zealand "genius"' association Mensa and yesterday completed a Rubix Cube in 1min 40sec.
On top of that it is obvious he has an appreciation of music far beyond his years.
"I read an article that says music heals the soul, and it does.''
