The Japan international has settled quickly since his arrival from Borussia Dortmund.
Ferdinand said: "I've been very, very impressed. I'd seen him play for Dortmund on TV and I looked on YouTube. He's been fantastic. He's quick, he's sharp, he has great awareness, he plays off both feet. I'm excited about playing with him and getting the season started. He's been one of the better players in Germany for the last few years. I think he'll bring that form to Manchester United. I think he'll be a great acquisition."