The Japan international, who missed the weekend's Asian Cup triumph due to injury, has joined Stuttgart on a free transfer, ending a five-year stay in the K-League.
The 24-year old has signed a three-and-a-half-year deal with Die Roten and will land at the Mercedes-Benz Arena later this week.
"I hope that I can contribute a lot to this team. I feel that my strengths are my ability to run, and in front of goal," he told the club's official website.
"In recent months I've felt a lot of stress, but another strength of mine is that I'm very resilient. I just need a few days to turn off, and then I'll be back in great condition.
"I know that the Bundesliga is a very physical, very high-level league. I'm looking forward to this challenge."