Vs Kaido
Zoro and Killer prepare their attack for Kaido, with Kaido noticing them and preparing to counter attack:
Kaido counterattacks but is unable to tag either of them and gets sliced cleanly (without either using hardening I might add). Killer attacks Kaido's neck, while Zoro attacks his body. We see Kaido grunt in pain ("UGH!!!") and specks of blood dislodged from his body:
In the following panels, Oda highlights how Killer's attack only managed to dent Kaido's neck but failed to break his skin. This means the specks of blood comes from Zoro's attack. Kaido further compliments them on their successful attack:
Zoro is left unsatisfied with the damage he dealt and comments on how he has yet to fully acclimatise to Enma:
Zoro's feat is rendered all the more impressive by the fact that — unless I'm misunderstanding something —Zoro's Rengoku Oni Giri did more damage to Kaido than Luffy's Kong Gun:
Contextualising Zoro's Offensive Feat
That Zoro could damage Kaido with a Rengoku Oni Giri is especially notable, because Oni Giri is one of Zoro's low tier Santoryu attacks (and is probably his weakest). My reasons below:
- The first Santoryu attack he used.
- Preskip He used it to finish Axe Hand Morgan.
- Postskip He used the upgraded version to finish Hyouzou
- It's normally his opening Santoryu attack
- Against Mihawk
- Against Daz Bones
- Attacks probably stronger than Oni Giri:
- Ul Tora Gari
- Zoro used it to counter the massive Punk Hazard Dragon and pushed it back
- Yasha Garasu
- Gave Oars many wounds that drew blood
- Attacks definitely stronger than Oni Giri:
- Nigori-Zake
- Overpowered Kaku's Bigan and cut him
- Cut Oars fang
- Gyuki Yuzume
- Destroyed T-Bone's attack and oneshot him
- Tatsumaki
- Nearly broke Kaku's Tekkai
- 108(0) Pound Cannon
- Oars admitted it would cut him pretty badly
- Bisected Pica's Golem
- Rokudo no Tsuji
- Sanzen Sekai
- Zoro's final attack against Mihawk
- Badly cut Oars up
- Bisected Pica's Golem and set the top half floating up several hundred metres
Maybe Oni Giri is not the weakest Santoryu attack, but it's a low tier Santoryu attack. Powerscaling Santoryu attacks it would be something like:
- Top Tier
- (Ichidai) Sanzen (Daisen) Sekai
- High tier
- Rokudo no Tsuji
- Nigori-Zake
- 108(0) Pound Cannon
- Mid Tier
- Kokujo Ou Tatsumaki
- Gyuki Yuzume
- Low Tier
- Karasuma Gari
- Hyokindama
- Daibutsu Giri
- Yasha Garasu
- Ushi Bari
- Toro Nagashi
- (Ul) Tora Gari
- (Rengoku) Oni Giri
Furthermore, given that Zoro did not use hardening on his Rengoku Oni Giri, it could likely have been made massively stronger.
Conclusion
Zoro once again blitzes a Yonkou (who was aware of him and actively trying to counterattack). Said Yonkou had himself just blitzed a Luffy that was using future sight. This is another demonstration of his insane attack speed. Furthermore, Zoro's attack power is further highlighted by the fact that a low tier Santoryu attack (and without hardening) was able to do some damage to Kaido and earn him compliments (more damage than was dealt by Kong Gun).