Held at Yebisu Garden Place, Hiroba, the event was supported by a huge media presence, with numerous national TV broadcasters and newspapers attending.
Hundreds of fans were given the opportunity to write messages of support on a giant flag bearing the new credit card, and also received a complimentary United keyring. Many messages were also left on an online microsite, created especially for fans who were unable to attend.
Celebrities including former Japan international Nobuhiro Takeda and model Nana Suzuki attended the event to join in the celebrations.
A gallery of photographs will shortly be available to view and an image of the flag will be uploaded before being sent to Old Trafford for the players to see.
These can be viewed from 31 August by visiting http://www.aplus.co.jp/card/mu/aplus/.