The playmaker, who is still only 25, signed a four-year deal with the Bundesliga side on Sunday after the 2013 Champions League finalists agreed a £6.3m deal with the Red Devils.
Kagawa, who failed to score in 20 Premier League appearances last season, joined United in a £14m deal in 2012 after playing a key role in Dortmund’s successive Bundesliga triumphs.
And United goalkeeper De Gea claimed that the Red Devils would miss Kagawa, wishing Kagawa all the best on his new adventure at Dortmund under former manager Jurgen Klopp.
— David De Gea (@D_DeGea) September 1, 2014
Earlier on Monday, Juan Mata described Kagawa as a “fantastic player” after the Japan playmaker quit Old Trafford.
“I would also like to wish all the best to Shinji Kagawa, a fantastic player but especially a great person,” Mata wrote on his blog, One Hour Behind.
“It’s been a pleasure to be his team-mate and I’m sure both Borussia Dortmund and fans everywhere will enjoy his football again.”
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