AEW Unified Champion Kazuchika Okada has achieved a major milestone. He already has a huge accolade to his name outside the Tony Khan-led promotion.Kazuchika Okada gained prominence during his legendary run in New Japan Pro-Wrestling. He made his AEW debut as a full-time talent last year and quickly became the Continental Champion. After holding the title for more than a year, Okada also won the International Championship at All In: Texas to become the first-ever Unified Champion.The Rainmaker has now completed 509 days as the AEW Continental Champion, as the title still exists even after unification. This makes him the longest-reigning singles champion in All Elite Wrestling history, surpassing the record set by Jade Cargill, who held the TBS Championship for 508 days.Okada is also the longest-reigning IWGP Heavyweight Champion in history. He held the coveted title for 720 days before losing it, and the record has yet to be surpassed.Sportskeeda Wrestling congratulates The Rainmaker on reaching the big milestone.Kazuchika Okada's AEW Unified Championship defense for Forbidden Door announcedAfter he became the AEW Unified Champion at All In: Texas, Okada was confronted by Swerve Strickland. Given the animosity between the two, the Tony Khan-led promotion has officially announced that The Rainmaker will defend his Unified Title against Strickland at Forbidden Door on August 24, 2025.AEW made the following announcement about the match on X:"#ForbiddenDoor PPV London Sunday, 8/24! AEW Unified Championship Kazuchika Okada vs Swerve Strickland @RainmakerXOkada wants revenge on @SwerveConfident for costing his friends @YoungBucks their EVP titles at All In, Swerve wants Okada's title! Okada vs Swerve LIVE on PPV!"The pay-per-view is set to take place at The O2 in London, England. It remains to be seen who walks out of Forbidden Door as the AEW Unified Champion.Who do you think will win in London? Drop your predictions using the discuss button.