The Japan international has left Lazio for Palace after a year in Rome.
He said on Palace's YouTube channel: "When I arrived at Lazio I felt that everyone expected a lot from me. Everyone is passionate about football in Italy and it's beautiful. But for me it was difficult especially because I arrived in the team where the best midfielder in Serie A, (Sergei) Milinkovic-Savic, played. And I had to take his place.
"So everyone expected a lot from me in the matches, but also during training. I felt that my normal performance was not enough. Then in the previous season Lazio had finished second in the table every time we lost we heard everyone booing and they told me that here in the Premier League, however, it doesn't happen. If you lose they support you."
On the choice of Palace, he continued: "I chose Palace because I had already been contacted in the winter, given that when Maurizio Sarri was at Lazio I never played. Many teams looked for me, I spoke to the president about leaving, but he said no that he wouldn't let me leave.
"I knew the history of Crystal Palace, they spoke to my manager. While I was thinking about what to do, Oliver Glasner sent me a message and said he wanted me as a signing for the summer. We started talking, but many clubs were looking for me and I didn't know what to do. I didn't play much at the beginning, then things changed. In the end I was undecided whether to stay at Lazio or go to Crystal Palace. But since I was little I told myself that my dream was to one day play in the Premier League.
"I talked a lot with Oliver Glasner and I think he is a great manager and he wanted me at all costs even when I was thinking of staying at Lazio in the end he prevailed. I've been following Palace since Glasner has been there, I've seen all the games. We have a physical team, with an important coach who gives importance to the defensive and offensive parts. We have talented players and we can do well."