The Japan international midfielder was rotated in and out of the Red Devils side last season, partly due to injuries, as they charged towards their 13th Premier League title.
The 24-year-old did not make the impact he would have liked during his maiden campaign in a United shirt nd has vowed to kick on in the new era of David Moyes's management.
"I wasn't satisfied with my overall performance but I played well in the second half of the season and started to get more and more confidence," Kagawa told Sports Illustrated. "Hopefully, I can keep that going at the Confederations Cup."
He added, "In this business, you need to be like Wayne Rooney or Robin van Persie and prove yourself if you want the ball. I want to be a player like them, which means I need results."
The former Borussia Dortmund midfielder made 26 appearances in his first season at Old Trafford, finding the back of the net six times.