England go on to play Pool B opponents Scotland on June 9 and Samoa on June 13 before the knock out stages take place on June 17 and 21.
They go into the tournament on the back of a third-place finish in the Six Nations but will be among the tournament favourites now they have their full Premiership complement back on board.
Coach Mark Mapletoft said:
"It's a big challenge and this is a must-win game at the start of the tournament but we've selected a team we believe can win the game."
England Under 20
15 Tom Homer (London Irish); 14 George Lowe (Harlequins), 13 Luke Eves (Bristol Rugby), 12 Greig Tonks (Leicester Tigers), 11 Jack Cobden (Leicester Tigers); 10 Rory Clegg (Newcastle Falcons), 9 Ben Youngs (Leicester Tigers); 1 Joe Marler (Harlequins), 2 Jamie George (Saracens), 3 Bob Baker (London Wasps); 4 Dan Williams (Gloucester Rugby), 5 James Gaskell (Sale Sharks); 6 Chris York (Harlequins), 7 Josh Ovens (Bath Rugby), 8 Carl Fearns (Sale Sharks)
Replacements
16 Ben Moon (Exeter Chiefs), 17 James Clark (London Irish), 18 Graham Kitchener, (Worcester Warriors), 19 Courtney Lawes (Northampton Saints), 20 Dave Lewis (Gloucester Rugby), 21 Rob Miller (Newcastle Falcons), 22 Henry Trinder (Gloucester Rugby)
Note: You can watch England U20 v Japan U20 live online at www.irb.com and on Eurosport2 from 11am on June 5 in the UK
