G4 Luffy doing nothing to Kaido is the only indicator needed that Sanji can't hurt Kaido lol
It seems that you can't damage Kaido with brawling combat unless you are Garp or Big Mom or you possess penetration CoA.

Swords and in general piercing damage are more efficient.

This is why Luffy could only tickle him. And Sanji can't hurt him too. His fire alone can't do anything to Kaido's body. Big Mom can resist sheer magma unless enough haki force is pinned and it's not magma by itself, Kaido can definitely resist pretty high temperatures so I find it cute when it is stated that Sanji's fire could remotely harm Kaido.
 
Its possible for Sanji to hurt Kaido with concentrated Diable Jambe or HM

- His concetrated DJ made the Kraken have the most "in pain" face out of all the attacks it took.



- Secondly, after Judge grabbed his DJ leg and threw him. Sanji switched to concentrated DJ....





This shows that Sanji thought concentrated DJ has a better time hurting the RS than normal DJ.

Is this why Judge used wall even though before he could handle normal DJ easily....




Sanji has only used concentrated DJ when he remembers his bad memories. Such as Kamabaka and his childhood. This also allowed him to transform into his HM mode as well.

We know Sanji's emotions allow his fire to increase.





Kiku losing an arm is the perfect time for Sanji to land a hot attack on Kaido. Because lets not forget Sanji wanted to kill Arlong for what he did to Nami.




I see either Sanji going to the roof and hurting Kaido in someway, or King stopping him from getting to the roof.
 
Its possible for Sanji to hurt Kaido with concentrated Diable Jambe or HM

- His concetrated DJ made the Kraken have the most "in pain" face out of all the attacks it took.



- Secondly, after Judge grabbed his DJ leg and threw him. Sanji switched to concentrated DJ....





This shows that Sanji thought concentrated DJ has a better time hurting the RS than normal DJ.

Is this why Judge used wall even though before he could handle normal DJ easily....




Sanji has only used concentrated DJ when he remembers his bad memories. Such as Kamabaka and his childhood. This also allowed him to transform into his HM mode as well.

We know Sanji's emotions allow his fire to increase.





Kiku losing an arm is the perfect time for Sanji to land a hot attack on Kaido. Because lets not forget Sanji wanted to kill Arlong for what he did to Nami.




I see either Sanji going to the roof and hurting Kaido in someway, or King stopping him from getting to the roof.
Don't forget that Sanji's DJ actually burned Jabra internally.


And Sanji is the first Strawhat to starting to break Pacifista apart.
 
Has it ever been explicitly mentioned that it's only a surface level burn? And has DJ ever been stated to internally burn after using it the first time against Jabra?
Red Hawk went straight through Hody's body but doesn't burn his bones. While DJ burn both the surface and the inside. And you can see in the panel that Sanji's DJ burned Jabra's bones and broke his ribcage after getting hit by it.
 
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