Kaido and Big Mom were both defeated during the Wano arc in One Piece , and their exact fate was left intentionally unclear. The story shows them falling into magma after their battles, but the manga did not give a confirmed death scene at that point.

What happened to Kaido

Kaido was beaten by Luffy after the huge fight in Wano, and he ended up deep underground with Big Mom near magma. Because the series never officially confirmed his death there, fans have long treated his status as unresolved.

What happened to Big Mom

Big Mom was defeated by Law and Kid, then sent crashing down beneath Wano as well. Like Kaido, she was not given a clear on-panel death confirmation, so her fate has stayed open to interpretation.

Why people still debate it

A lot of discussion continues because both characters are extremely durable and the story left room for survival. Online fan theories range from “they died in the magma” to “they survived and could return later,” but those are theories rather than confirmed canon.

Simple take

In canon, they were defeated and buried under Wano after falling into magma , but their deaths were not explicitly confirmed in the story at that point. That’s why people still talk about whether they’re dead, alive, or coming back later.