We are pleased to announce that a Geant4 20th anniversary celebration symposium and the 19th collaboration meeting will be held at Okinawa Convention Center. The 20th anniversary symposium will be held on September 29th. It will have a plenary session of invited speakers and a ceremony party, looking back over the past score years of the Geant4 collaboration, celebrating the present success, and discussing the future. Note that the symposium is open for non-collaborators, but registration is required for attendance. After the symposium, we will have the annual collaboration meeting for September 30 - October 4th. This meeting is limited to Geant4 collaborators and persons invited by the Steering Board.