Leicester Tigers youngsters Greig Tonks, Ben Youngs and Jack Cobden, who was making his under-20s debut, played their part as England ran in six tries in steady rain at the Prince Chichibu Stadium in Tokyo.
England played the bulk of the second half with 14 men after prop Joe Marler was sent off for allegedly striking an opponent - and 10 minutes with 13 after Wasps prop Bob Baker was sin-binned.
But England dug deep to win their opening Pool B game through tries from George Lowe, Luke Eves, Chris York, Carl Fearns, Josh Ovens and Courtney Lawes also touching down. Kicker Tom Homer added 13 more points.
Head coach Mark Mapletoft said: “Six tries in those conditions represents a pretty good start and to keep the opposition scoreless is pleasing.”
England Under-20s
Tom Homer (London Irish)
George Lowe (Harlequins)
Luke Eves (Bristol Rugby)
Greig Tonks (Leicester Tigers)
Jack Cobden (Leicester Tigers)
Rory Clegg (Newcastle Falcons)
Ben Youngs (Leicester Tigers)
Joe Marler (Harlequins)
Jamie George (Saracens)
Bob Baker (London Wasps)
Dan Williams (Gloucester Rugby)
James Gaskell (Sale Sharks)
Chris York (Harlequins)
Josh Ovens (Bath Rugby)
Carl Fearns (Sale Sharks)
Replacements
James Clark (London Irish)
Ben Moon (Exeter Chiefs)
Courtney Lawes (Northampton Saints)
Dave Lewis (Gloucester Rugby)
Rob Miller (Newcastle Falcons)
Henry Trinder (Gloucester Rugby)
Graham Kitchener (Worcester Warriors)
