Kim's family moved from Queenstown to Nelson soon after he had represented Otago in the national interprovincial tournament at Balmacewen in 2012.
Kim (18) shot a 2-under-par 70 to be one shot ahead of Jake Hallinan (Weedons) who, with 71, shot the only other sub-par round on the Turner-designed course.
Kim leads the under-19 section while Andrew Drummond (Greenacres) leads the under-17 event by one shot from Cromwell's Inia Logan, who is in a three-way tie for second after firing 73.
Waitemata's Ha Bin Suh leads the under-15 event with 72 while in the under-13 section Oak Archvarin (North Shore) leads on 83.
Brooke Hamilton (Maungakeikei) has opened up a substantial lead in the girls event after a great round of 70.
Hamilton goes into today's second round with an eight-shot lead over Laura Hoskin (Arrowtown) and Russley's Jessica Crosbie.
Kim's round of 70 has launched the under-19 Tasman team into an impressive 14-stroke lead in the team event.
He was ably supported by Andrew Drummond (72), Nick Hanna (73) and Chas Craig (74), leaving Canterbury with plenty of work to do today and tomorrow.
Otago was a disappointing third, a further 13 shots back in third place, with Southland looking set to take the wooden spoon.
Otago dominated the under-16 event and is 11 shots clear of Canterbury with two rounds to play.
Logan led the way with 73 while Terry Kim (Queenstown) finished with two birdies for 74.
They were supported by Jacob Bleach and Ryan Whelan, who scored 79 each, while No 5 Callum Judkins (Queenstown) also tidied his round up with late birdies for 80.
