Birth! Combine Super Warrior, His Name is Gotenks!! (誕生！合体超戦士 その名は、ゴテンクス!! Tanjō! Gattai Chō Senshi Sono Na wa, Gotenkusu!!) is the one hundred thirty-eight episode of Dragon Ball Z Kai. Its Japanese air date is November 23, 2014. Its American air date is November 4, 2017.
After some dubious persuasion from Goku, Old Kai reveals he has the ability to draw out someone's true power beyond their limits. This turns out to be a lengthy process that can take over a day to complete. Meanwhile, Goten and Trunks try out the Fusion Dance for real, but an error in the Fusion Dance results in the merged fighter, Gotenks, ending up with a failed transformation. After another failure, Goten and Trunks eventually perform a successful fusion and transform into the true Gotenks. Gotenks is confident that he can defeat Majin Buu with his current power level. He goes off in search of Majin Buu despite Piccolo's warnings.