No. She is not.
It was just a joke by Japanese football fans, but the English media took it seriously.
According to some English football sites, the new boy of Manchester United - Shinji Kagawa is dating a Japanese av porn star name Ameri Ichinose which is not true. They don't know each other and are not dating.
It all started from a Japan porno magazine where it claims Ameri Ichinose has a quiet boyfriend and one idiot tweeted it is Shinji Kagawa. Another idiot work in England media took it seriously and published a total make-up story on a reputable media web sites.
Ameri Ichinose also known as Ayaka Misora or Erika Kurisu was born in 1987, 167cm height with 35-22-33 measures and retired from filming adult video in 2010.
Ameri Ichinose Photo.