Captained by Coleg Gwent blindside Robert Brookson, Wales will be out to repeat last year's victory against the same opposition. There is also a starting spot for Dragons scrum-half Dan Babos, who featured for Wales U20 earlier this year and has already made an impact at regional level.
"The South Africans are going to test us physically and mentally," says head coach Chris Horsman. "We told the players they're going to have to go to a place they haven't been to before."
"We know the type of rugby South Africa play: they're very big and physical up front, with a lot of pace and skill out wide. It'll certainly be a challenge, but that's what we're hoping for because this is what the U18 programme is all about."
On Wednesday, the squad headed to Cape Town for a training session against Western Province U19s. "We're trying to make the most of being out here," Horsman says. "It's been really interesting. It's a very different cultural experience for the players: the whole landscape of the country and being in places like Stellenbosch is great for them."
A significant number of the players who featured in last year's successful series - which saw Wales claim two victories and push France close in the final match - have swiftly progressed to Wales U20 and Wales Sevens, which has served to increase the profile of U18 rugby.
Wales U18 team to face SA Schools
15 Ioan Lloyd (Clifton College/Bristol/Exiles), 14 Ewan Rosser (Coleg Gwent/Dragons), 13 Joe Roberts (Coleg Sir Gar/Scarlets), 12 Aneurin Owen (Ysgol Gyfun Gwynllyw/Dragons), 11 Louis Rees-Zammit (Hartpury College/Exiles), 10 Sam Costelow (Oakham School/Exiles), 9 Dan Babos (Dragons Academy/Dragons), 1 Garyn Phillips (Coleg y Cymoedd/Cardiff Blues), 2 Cameron Lewis (Coleg Sir Gar/Ospreys), 3 Luke Yendle (Newport High/Dragons), 4 Teddy Williams (Ysgol Glantaf/Cardiff Blues), 5 Jac Price (Coleg Sir Gar/Scarlets), 6 Robert Brookson (c) (Coleg Gwent/Dragons), 7 Jac Morgan (Coleg Sir Gar/Scarlets), 8 Ioan Davies (Coleg y Cymoedd/Cardiff Blues)
16 Llew Phillips-Taylor (Coleg Sir Gar/Scarlets), 17 Callum Williams (Maes y Gwendraeth/Scarlets), 18 Ben Warren (Coleg y Cymoedd/Cardiff Blues), 19 Archie Griffin (Marlborough College/Exiles), 20 Carwyn Tuipulotu (Sedbergh School/Scarlets), 21 Olly White (Llandovery College/RGC), 22 Morgan French (Bromsgrove/Worcester), 23 Ellis Bevan (Bryanston/Exiles), 24 Evan Lloyd (Coleg Gwent/Dragons), 25 Harri Doel (Coleg Sir Gar/Scarlets), 26 Morgan Richards (Newport High/Dragons), 27 Osian Knott (Coleg Sir Gar/Scarlets)