Kagawa had been linked with other clubs but the chance to work with Ferguson was far too appealing, the 23-year-old who scored 21 goals in 49 league games for Borussia Dortmund, explained.
"There was some talking going on with other clubs, but Manchester [United] were the first to make me a formal offer and the more I talked to them, the more I felt Manchester was the place for me to be.
"I met (Ferguson) and contacted him a few times afterwards. I thought we hit it off, which meant a lot to me. He told me, "Don't worry about a thing, trust me. I would love it if you could take on this huge challenge".
"And when a legendary man like him says that to you, it carries a lot of weight."