A Dortmund source told the Daily Express: "Shinji is an offensive midfielder who plays centrally in a position just behind a striker or two strikers. He has very good technique and is also fast. He fitted into Dortmund's style perfectly because the coach, Jurgen Klopp, doesn't want his central midfield players to hold the ball up too much. That slows things down. He wants players who will distribute the ball quickly and think swiftly. Shinji does that.
"He is a dedicated professional and is always looking to improve himself. Nobody expected him to make the progress he has in Germany."
There have only been four Japanese players in the Premier League. Junichi Inamoto played for Fulham, West Brom and Cardiff between 2002-06, Kazayuki Toda was at Spurs briefly in 2002, Hidetoshi Nakata was at Bolton between 2005-06 and Ryo Miyaichi is currently at the Reebok on loan from Arsenal.
The source added: "Shinji's dream is to become the first Japanese professional to make the serious breakthrough in England.
"There is no doubt he has the attributes to play in England. The Bundesliga is physical like the Premier League, but he has been able to deal with that. It is not a problem."