One Piece Episode 991 English Subbed Episode Title:Enemy or Ally? Luffy and Yamato!Episode Description:Perospero arrives at Onigashima to stop the Emperor's alliance and revenge against Luffy, King, and Marco. Big Mom corners Usopp and Chopper until Prometheus calls her because he found Nami's group. Orochi begins Momonosuke's execution as the some of the alliance watch on. Luffy questions Yamato's motive and attacks him, who blocks Luffy's attacks. When Luffy attacks Yamato with Red Hawk, it reminds him of his battle against Ace who came to Wano for Kaido's head.