It's the summer of 2012 and Sir Alex Ferguson is spending his days masterminding a way of wrestling the Premier League title back from Manchester City.
There is talk Robin van Persie might become available, but Arsene Wenger convinces his captain to sign a new contract at Arsenal.
It's a blow for Roberto Mancini and City, who had hoped to lure the Dutch striker to Etihad Stadium. But Ferguson isn't bothered. He's already decided on his new system, with Kagawa playing behind Wayne Rooney.
The pair start together in the first game of the season at Everton. And although it doesn't go to plan, there are signs Rooney and Kagawa are already developing an understanding.
Inspired by Rooney's goals (he finishes as the Premier League's top scorer) and Kagawa's assists (he ends the season with 40) United win a record 20th title.
Their partnership is so good the tabloids brand them "Kwazza" and United reject a £150 million bid for the pair from Real Madrid.
After Antonio Valencia asks to have his old No. 25 shirt back, Kagawa is offered the No. 7. He accepts and stays at United for the next 10 years, retiring just after his 35th birthday as one of Old Trafford's great No. 7s alongside George Best, Bryan Robson, Eric Cantona and Cristiano Ronaldo.
But, of course, Van Persie didn't sign a new contract at Arsenal. And he did join United. Ferguson's decision was ultimately vindicated. He retired as a champion, beating his final rival—Mancini's City.
Van Persie's arrival, just months after Kagawa's, condemned the 24-year-old Kagawa to a life on the left. And on the bench.
Since August 2012, United have played 93 games. But Kagawa, Van Persie and Rooney have started together just 11 times.
Injuries to all three during that time have been a factor but the point still stands: Ferguson, and now David Moyes, have struggled to fit them all into the same team.
If anything, Kagawa's prospects of first-team football have diminished even further.
Adnan Januzaj has established himself as a fixture in the squad and in January, Moyes splashed a club record £37.1 million on Juan Mata.
In the four games since Mata's arrival from Chelsea, Kagawa has twice been an unused substitute and twice been left out of the 18-man squad entirely.
He might get a chance to impress next week against Olympiacos with Mata unavailable for the Champions League. But, assuming there's not an injury crisis, Kagawa's future looks bleak.
His fans will say he's not had a chance to prove himself in his preferred position, and that much is true.
But he's also not replicated the form he showed in two years at Dortmund. There have been flashes of brilliance—a Premier League hat-trick against Norwich last season among them—but he hasn't been consistently good enough.
Van Persie, Mata, Ferguson and Moyes have played their part in Kagawa's downfall, but he must take a portion of the blame as well.
So where does he go from here?
Kagawa still has more than two years on his contract and if United don't want to let him leave they don't have to.
But with Moyes struggling to find a place for him on the bench, never mind the first team, it's unlikely he'll stand in his way if the right offer comes along.
Ask any one of the pack of Japanese journalists who follow Kagawa's every move and they'll tell you he'll have plenty of offers in the summer. And some of them will start to look pretty inviting if he spends the next three months in the shadows.
It's the summer of 2014 and Kagawa leaves Old Trafford for the last time. It could all have been so different.