Where “Splatoon 3's record Japanese launch” started

Nintendo, on Retail, Sep 9, 2022. It reached 4 platforms in 9 weeks.

LineageKey steps, 8 of 15. Lines follow time and platform
「スプラトゥーン3」とセブン‐イレブンのコラボキャンペーンが9月1日スタート。コラボメニュー6種と,限定グッズの情報が明らかに7-ElevenBefore the first postSplatoon™ 3 for Nintendo Switch - Nintendo Official SiteNintendoFirst postPlatform jumpPressCommercialObserved peakOwner responseAfterlifePatient zero