Wales Under 18 wing Dafydd Howells, Blues and Wales sevens centre Owen Williams, Scarlets hooker Emyr Phillips and Ospreys' James King will all make their international debut at Hanazono Field this weekend.
Phillips will be joined in the front-row by RBS 6 Nations squad members Ryan Bevington (Ospreys) and Scott Andrews (Blues) and Captain Bradley Davies will pack down alongside his Blues teammate Lou Reed.
In the back-row Andrew Coombs (Dragons) wears six for the first time for Wales, King will play at openside flanker and Rob McCusker (Scarlets) makes his first start for Wales at number eight.
Lloyd Williams (Blues) and Dan Biggar (Ospreys) who both played in all five six nations matches partner each other at half-back.
Jonathan Spratt (Ospreys) makes his first appearance for Wales since 2009 and lines up alongside Williams who makes his debut.
Wales Under 20 wing Harry Robinson will earn his second cap and Howells, who recently won the Principality Premiership Newcomer of the Season award, starts on the other wing.
Liam Williams (Scarlets) is named at full-back and will make his fourth appearance for Wales.
There are four uncapped players on the bench with Ospreys hooker Scott Baldwin lining up alongside regional teammate Dan Baker who made 25 appearances for Swansea RFC this season. Blues captain Andries Pretorius is named in a matchday squad for the first-time as is 20-year-old fly-half Rhys Patchell. Props Rhys Gill (Saracens) and Rhodri Jones (Scarlets) are joined by Gloucester-bound scrum-half Tavis Knoyle and Dragons back Tom Prydie who returns to the Welsh squad for the first time since 2010.
"The squad have really worked hard over the last couple of weeks and they are ready to get out and play," said Head Coach for the Japan tour Robin McBryde.
"We have been impressed with training and all the boys have put their hand up to try and get into the test team.
"They are eager to get out there now, pull on the jersey and show what they can do.
"It's a fantastic opportunity for them and they know the importance of wearing the jersey and representing our nation."
WALES
Liam Williams (Scarlets), Harry Robinson (Blues), Owen Williams (Blues), Jonathan Spratt (Ospreys), Dafydd Howells (Ospreys), Dan Biggar (Ospreys), Lloyd Williams (Blues), Ryan Bevington (Ospreys), Emyr Phillips (Scarlets), Scott Andrews (Blues), Bradley Davies (CAPT) (Blues), Lou Reed (Blues), Andrew Coombs (Dragons), James King (Ospreys), Rob McCusker (Scarlets).
Replacements: Scott Baldwin (Ospreys), Rhys Gill (Saracens), Rhodri Jones (Scarlets), Andries Pretorius (Blues), Dan Baker (Ospreys), Tavis Knoyle (Scarlets), Rhys Patchell (Blues), Tom Prydie (Dragons).
