Answer
Shinji Kagawa returned to Borussia Dortmund after leaving Manchester United. Kagawa played for Dortmund from 2010 to 2012, before joining United for £17 million. He was unable to break into the first team at United and was loaned back to Dortmund for the 2014-15 season. He then returned to Dortmund on a permanent basis in 2015.