England beat South Africa 21-14 to win the Tokyo Sevens final at the city's Prince Chichibu Memorial Stadium.
Tries from Charlie Hayter, Tom Mitchell and Phil Burgess gave England victory in the final, moving them above Australia into the fourth qualifying spot for the 2016 Olympic Games.
Great Britain's hopes of qualification for the Games in Rio rest entirely on England's World Series performance.
Simon Amor's side beat France in the quarter-final and Canada in the semis.
"The way the guys fought for that win was brilliant," said the England coach.
"It's fantastic for us and a great climax for us to go back to the UK now. I am so proud for the players, they've worked so hard for this."
Sevens is making its Olympic debut next year and England's men's and women's teams were chosen to compete for Team GB in qualifying after finishing higher than Wales and Scotland in the 2013-14 Sevens World Series.
If they earn Team GB a place, players from all three countries will be available for selection.
The two remaining legs of the World Series will be played in Glasgow - where England have been drawn in the same pool as Australia, France and Russia - and Twickenham in May.
Scotland, beaten by New Zealand in the Plate final in Tokyo, and Wales have both been drawn in the same group alongside Fiji and Portugal in the Glasgow event.
|World Series standings|
|22 points for final win; top four gain Olympic qualification|