You know how to read ?
Kid and killer already faced KAIDO they witnessed it personally.
They didn't hear any rumors.
This is the second time that they are facing him, KILLER is the most calculating of all, would he be lying?
Stop denying your stupid shit.
Kid and killer already faced KAIDO they witnessed it personally.
They didn't hear any rumors.
This is the second time that they are facing him, KILLER is the most calculating of all, would he be lying?
Stop denying your stupid shit.
Killer (a person) says Kaido is the strongest.
He doesn't need to address it as a rumor, it's the truth for him.
Oda is telling us, people within the story say Kaido is the strongest.
Case and point being Killer literally calling Kaido the strongest pirate.
That doesn't confirm anything, because Oda as the author isn't calling him the strongest.
He's saying people in his story think of him as the strongest.
For Mihawk for example, he is the strongest in both perception and reality.