Amazon Japan launched Assassin's Creed: Mirage on May 25. The store page indicated that the game will release on October 10.
Amazon JP
However, Ubisoft's official announcement is yet to come.
Assassin's Creed: Mirage is an upcoming action-adventure game developed by Ubisoft Bordeaux and published by Ubisoft. It will be the 13th major installment in the Assassin's Creed series and the successor to 2020's Assassin's Creed Valhalla.
Source: Amazon Japan