Episode 991

"Enemy or Ally? Luffy and Yamato!" is the 991st episode of the One Piece anime.

Short Summary
Perospero approaches Onigashima on his own. Big Mom leaves Chopper to look for Zeus. Luffy is hostile to Yamato for being Kaidou's son.

Long Summary
Angry that the Big Mom Pirates' ship was knocked down the waterfall twice, Perospero rides to Onigashima on his candy slug. He swears revenge on King and Marco for knocking the ship down.

Chopper's tank fires several rounds at Big Mom but she is unharmed by the fire. She prepares to use her Devil Fruit powers on Usopp and Chopper, but upon hearing Prometheus' call, she walks away. Although the tank is unharmed, a transformation switch is activated, turning the tank into the lower half of the General Franky. Chopper must unite it with the Kurosai FR-U IV to form the full General Franky.

Big Mom walks through the halls in search of Zeus, creating homies with pieces of her soul. Nami, knowing she could not win in a battle against Big Mom, decides to run into the performance hall with Zeus to avoid her. Meanwhile, Zoro is in the halls but is surrounded on both sides. He encounters a group of Gifters who offer him a spot in the Beasts Pirates. Zoro refuses and cuts the enemies down.

Robin and Jinbe are among the partygoers and they spot Hyogoro, and they are glad that the samurai successfully entered the castle. Robin is harassed by a drunken Beast Pirate but she knocks him out. Then, Orochi appears on the party room balcony, showing Momonosuke tied to a cross and preparing to execute him. Kaidou is disappointed that Orochi interrupted his party.

The medical team tends to Ulti's mouth injury and helps her regain consciousness. Page One, who had no injury other than a dislocated jaw, goes to chase after Yamato. In the hallway, Yamato attempts to speak with Luffy but Luffy refuses to listen because he was Kaidou's son. He unleashes several attacks on Yamato, who defends himself against the attacks. This reminds Yamato of the time he battled with Ace.

Anime Notes

 * The anime adds the following:
 * Big Mom continuing to chase Usopp and Chopper. The moment when she hit the Brachio Tank V (which caused it to later activate the leg parts of the General Franky robot) is also seen.
 * Big Mom leaving after Prometheus notifies her of the location of Nami's group.
 * Robin and Jinbe arriving at the Skull Dome. The former also knocks out a Beasts Pirates member who tried to flirt with her.
 * Kaidou criticizing Orochi.
 * Luffy breaking free from Yamato's grip.
 * A brief flashback of Yamato's fight against Ace.
 * The anime extends the following:
 * The Gifters trying to persuade Zoro to join Kaidou.
 * Zoro's fight against the Gifters and other subordinates.
 * Page One calling for the Beasts Pirates' medical team to check up on Ulti.
 * Luffy and Yamato's fight.