When the Wano arc first began, most fans expected the conflict to revolve entirely around Luffy’s battle against Kaido. However, Eiichiro Oda dramatically changed the scale of the war by bringing Big Mom into Wano. Instead of acting as a secondary antagonist, Big Mom became one of the most important forces in the arc, influencing everything from the alliance dynamics to Luffy’s growth during the battle against Kaido.
Her return carried major narrative weight because her conflict with Luffy had already been building since the Whole Cake Island arc. Luffy challenged her authority long before he was ready to fight Kaido, and her arrival in Wano turned the rebellion into a war against two Yonko instead of one. This shift completely transformed the stakes of the arc and forced the Worst Generation to evolve much faster than expected.
Big Mom’s role also changed the direction of several major characters, especially Trafalgar Law and Eustass Kid, whose development became tied directly to defeating her during the Onigashima raid.
Why Big Mom Came to Wano in the First Place
Big Mom’s arrival in Wano was not random. Her pursuit of Luffy began during the Whole Cake Island arc after he invaded Totto Land, defeated Charlotte Katakuri, and escaped her territory. Luffy openly declared that he would defeat Big Mom one day, damaging her reputation as one of the Four Emperors.
Instead of ignoring the insult, Big Mom followed the Straw Hats into Wano. This decision immediately escalated the danger surrounding Kaido’s territory. At first, Kaido himself viewed her arrival as a threat rather than support, even ordering his forces to stop her from entering Wano.
However, the two former Rocks Pirates members eventually formed an alliance, creating one of the most dangerous pirate partnerships in One Piece history. Their temporary alliance changed the entire balance of power during the raid on Onigashima and forced the Worst Generation into an impossible situation.
Big Mom’s presence fundamentally changed Luffy’s fight against Kaido because Luffy was no longer fighting a single Emperor. Instead, the rooftop battle became a war against two Yonko working together. Kaido and Big Mom’s combined strength overwhelmed the Supernovas early in the battle and demonstrated how massive the power gap still was.
One of the clearest examples of this was their combined attack, Hakai, which nearly wiped out the entire Worst Generation team on the rooftop. The attack forced the alliance fighters to separate Big Mom and Kaido because defeating them together seemed impossible.
This decision had enormous consequences for Luffy’s development. Without Big Mom distracting Law and Kid, Luffy would likely have faced Kaido’s full strength much earlier and lost permanently. Instead, the split battle structure allowed Luffy time to improve his mastery of Advanced Conqueror’s Haki and eventually unlock Gear 5.
Big Mom indirectly created the conditions necessary for Luffy to survive long enough to challenge Kaido equally.
Big Mom’s Role in Kid and Law’s Growth
Big Mom’s role in Wano was also critical for Trafalgar Law and Eustass Kid. Before the raid, both characters were often viewed as rivals to Luffy but lacked a defining victory against a top-tier opponent. That changed during the Onigashima battle.
By facing Big Mom together, Law and Kid finally proved they belonged among the strongest pirates of the new generation. Their battle pushed both characters to awaken their Devil Fruit powers and forced them to fight creatively against an opponent with overwhelming durability and Haki.
Unlike Kaido’s direct combat style, Big Mom’s Soul-Soul Fruit abilities created unpredictable attacks that demanded teamwork and strategy. This allowed Law and Kid to evolve in ways that would not have happened during a traditional one-on-one battle.
Their eventual victory over Big Mom became one of the most important moments in the Wano arc because it symbolized the decline of the old Yonko era.
Big Mom’s involvement in Wano also expanded Kaido’s backstory. The arc revealed that both Yonko were former members of the legendary Rocks Pirates, one of the most feared crews in One Piece history.
Their shared history explained why their alliance was so dangerous. Even though they constantly argued and threatened each other, they still possessed remarkable combat synergy. Their bond added another layer to the Wano conflict because the battle was no longer just about liberating Wano from Kaido. It became a clash between the old pirate generation and the rising era led by Luffy and the Worst Generation.
Big Mom also played a key role in humanizing Kaido slightly. Through their conversations and flashbacks, viewers saw traces of their long history together, including Big Mom’s claim that Kaido owed her a lifelong debt connected to his Devil Fruit.
Why Big Mom’s Return Was Necessary for the Wano Arc
Although some fans debated whether Big Mom should have remained the main antagonist for a later arc, her role in Wano ultimately strengthened the scale of the story. Her arrival elevated the conflict from a rebellion into a historic Yonko war that permanently changed the balance of power in the One Piece world.
Most importantly, Big Mom’s presence prevented the Wano arc from becoming a straightforward Luffy-versus-Kaido story. She created additional conflicts, empowered Kid and Law’s development, and forced the alliance to divide its resources strategically during the raid.
By the end of Wano, both Kaido and Big Mom had fallen, marking the end of an era dominated by the old Emperors. Their defeats allowed Luffy to rise officially as one of the new Yonko, signaling the beginning of the Final Saga.
Without Big Mom’s return, the Wano arc would still have been massive, but it would not have carried the same scale, tension, or world-changing impact that made it one of One Piece’s most important storylines.
Additionally, Big Mom’s defeat carried long-term consequences beyond the Wano arc itself. Her fall, alongside Kaido’s, marked a decisive shift in the global power structure, weakening the dominance of the old Yonko generation. This moment opened the door for rising pirates like Luffy, Law, and Kid to gain recognition on a global scale.
It also sent waves across the world, influencing the World Government and other pirate crews to reassess their strategies. Big Mom’s presence in Wano was not just about adding another powerful enemy; it was essential in signaling the beginning of a new era where the balance of power would no longer remain the same.