The Japan international has arrived from CSKA Moscow on a Bosman.
"It's been an exciting time and I'm really happy to be here," he said.
"I always said that I would play in Serie A and wear the number 10 shirt. So I was desperate to come here and play.
"I'm delighted about the interest in me and I want to thank Galliani and the club for this transfer. I now want to show on the pitch what can I do. I was destined to come here.
"I wanted to come here, wanted to be a champion here with the club.
"I knew all the players as a child - I watched the matches on tv every week. Serie A is the most famous League in Japan.
"I understand there are high expectations and I've got to show what I'm capable of. I want to score many goals, assists - I'll do my best.
"As I mentioned, I need to score goals, get assist and there are many things I need to do and can do. I don't think the side are doing that bad, I saw the match on Monday - the boys are great.
"I have said in many interviews, for me football is my life. I'm not so interested in the city in which I play, I only want to train hard, rest well and win.
"That is what matters to me in my life . I know the club will help me a lot straight from the start.
"I can play in any position but if I could choose, I would like to play behind the striker, as an attacking midfielder.
"My heart said Milan. That's all I can say."
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