Stage 1 (Qualifications) Round 1-3 are Best of 5Even MS and WS matches are played to best of 5 now?
Stage 2 (Main Draw) Round 4 or R64 till the Finals are Best of 7. This starts on Friday 26 January 2024.
See item (10) in the playing system for All Japan 2024 https://jtta.s3.ap-northeast-1.amaz...2023/12/12120402/2024zennihon_youkou_1212.pdf
This system is the same as in previous editions of All Japan.
"各種目ともトーナメント方式による。男女シングルスの第 1 ステージは 11 ポイント 5 ゲームマッチ、第 2 ステージ(ベスト 32 決定戦以降)は 11 ポイント 7 ゲームマッチ、他の種目はすべて 11 ポイント 5 ゲームマッチで行なう。
Each event will be held in a tournament format. The first stage for men's and women's singles will be an 11-point, 5-game match, the second stage will be an 11-point, 7-game match, and all other events (Junior events and Doubles) will be an 11-point, 5-game match."