Pool D captains, including Wales's Scott Andrews, at the Tokyo launch ahead of the tournament kick-off.
Ospreys academy and Aberavon back row Justin Tipuric will lead Wales Under 20 in their opening match of the IRB Junior World Championship, against Tonga in Saga tomorrow (Friday, 11am UK time).
Three players will earn their first Wales Under 20 caps in this game with uncapped trio Llanelli of full-back Daniel Newton, Carmarthen Quins centre Jason Harries and Glamorgan Wanderers scrum-half Lloyd Williams all earning their places in the starting line-up.
Two other uncapped players, Owen Evans of Llandovery and Jamie Davies of Carmarthen Quins, start on the bench.
Squad captain Scott Andrews, Dragons academy outside-half Dai Langdon and Cross Keys scrum half / wing James Leadbeater are unavailable for this game with minor injuries but should all be available for Wales' second game of the championship against Canada on Tuesday. Ospreys academy no 8 Rory Pitman goes straight into the starting line-up after joining up with the squad from New Zealand where he has been playing with Air New Zealand Cup side Taranaki
Wales head coach Phil Davies said, "The boys have worked extremely hard since we arrived in Japan at the end of last week. The new caps have all performed well in training and deserve their opportunity on the field tomorrow. We are confident in these players and hopeful this team will bring us a winning start to the tournament. However, we have five games over 16 days and therefore a 26-man effort is undoubtedly required in order to do well for Wales in this campaign. Rory (Pitman) is in great shape, he has trained well and fitted straight back into the group well, there is no doubt his time in New Zealand has helped him.
"Being in Japan is providing a new cultural experience for the players, alongside the rugby experience. We visited the Atomic Bomb Museum in Nagasaki this week, an unbelievable experience for the players and management."
Wales Under 20 v Tonga, Friday 5 June, 11am UK time (7pm local time):
Daniel Newton (Scarlets academy/ Llanelli); Jamie Loxton (Blues academy / Glamorgan Wanderers), Jason Harries (Carmarthen Quins), Ashley Beck (vice-captain, Ospreys academy / Aberavon), Nick Reynolds (Llanelli); Matthew Jarvis (Ospreys academy / Neath), Lloyd Williams (Blues academy / Glamorgan Wanderers); Aaron Coundley (Dragons academy /Ebbw Vale), Rhys Williams (Blues academy / Pontypridd), Simon Gardiner (Scarlets academy / Llanelli), James King (Ospreys academy / Aberavon), Ashley Sweet (Dragons academy / Cross Keys), Justin Tipuric (capt, Ospreys academy / Aberavon), Rhys Jenkins (Dragons academy / Ebbw Vale), Rory Pitman (Ospreys academy / Bridgend / Taranaki)
Replacements: Owen Evans (Llandovery), Craig Attwell (Dragons academy/ Newbridge), Josh Navidi (Blues academy / Glamorgan Wanderers), James Thomas (Dragons academy / Ebbw Vale), Rhys Downes (Blues academy / Pontypridd), Jamie Davies (Carmarthen Quins), Scott Williams (Scarlets academy / Llanelli), Dan Partridge (Cardiff)
Wales Pool D fixtures (all at Best Amenity Stadium, Saga):
Wales v Tonga, Friday 5 June
Wales v Canada, Tuesday 9 June
Wales v Australia, Saturday 13 June
Beating Merthyr has boosted Carmarthen Quins hopes of reaching a top eight spot in the Principality Premiership. Quins captain Haydn Pugh is delighted with his team's progress and is determined that everyone from the Under 6s through to the senior team, enjoys the ride.
When the Wales squad were asked to nominate individuals who played a big part in their early playing days, Wales and Dragons full back and wing Hallam Amos thought of his former Monmouth School rugby coach John Bevan.
Sam Cross and Luke Treharne have been named as co-captains of the Wales Sevens side as head coach Gareth Williams names his 12-man squad to play in the first leg of the HSBC World Series in Dubai next weekend.
Bedwas head coach Steve Law and players Nicky Griffiths and Alun Rees extol the virtues of the close knit club as they prepare to host third place RGC 1404 - who are one place head of them on the Principality Premiership points table - on Saturday.
Many of the Wales squad have said Diolch (thank you) to someone who played an important part in their early playing days by nominating them to be invited to the Wales v South Africa match. One person, Gowerton Comprehensive geography teacher Mr Dean Mason was nominated by two of his former pupils, Dan Biggar and Sam Davies.
The second WRU disability rugby pilot has been delivered, this time in Caerphilly schools, culminating in a festival at the Caerphilly Centre of Sporting Excellence, Ystrad Mynach tomorrow. Plans are in place to set up a Disability Rugby Club in Newbridge to provide long-term playing opportunities.
WRU TV: Hear from inside the Wales camp as Neil Jenkins discusses this weekend's clash with South Africa and how the squad are looking to put in a strong performance to round of the 2016 Under Armour Series