Ryo believes Arsenal will face a stern test when they take on Urawa Reds in the final match of the Asia Tour on Friday.
Only two European teams have ever won the Saitama City Cup since its inception in 2004, while the hosts are currently fourth in the J League.
"There's a great environment in the stadium and they have a very good standing in the J League. They have good momentum right now"
Ryo expects them to pose a major challenge, but will go into the game in confident mood following his goal against Nagoya Grampus on Monday.
“I am from that part of Japan so I was very happy to score that goal,” he said. “I also appreciate my team-mates allowing me the chance to take the penalty.
“It was an extremely fruitful and valuable experience for me and it was the best night you could imagine. I was very happy that I was able to participate in a good match.
“My impression of this Urawa Reds team is that they are very well-known in the J League for their passionate supporters. There's a great environment in the stadium and they have a very good standing in the J League. They have good momentum right now.”
Having suffered a serious injury while on loan at Wogan Athletic last season, Ryo is getting back to full fitness - but accepts there is plenty of work still to be done.
“I did say that my fitness level is not 100 per cent yet but fortunately we are still in pre-season,” he said. “I know that I need to condition myself to the full and to play for Arsenal I know that I need to brush up my skills.
“I also know that I have to speed up the amount of time I need to make the right [decisions]. For all the practice that a professional player is required to have, I think I need to brush myself up.”