Full summary, thanks to redon from Arlong Park Forums.
Chapter 1,024: "A certain someone (某 (なにがし))".
Characters in the 2nd part of the special poster for World Popularity Poll: Gol D. Roger (in the sky like Kaidou and Big Mom in the 1st part of the poster), Crocodile, Enel, Mr. 2, Vivi, Carue, Nami, Sanji, Brook, Chopper, Luffy, Robin, Jinbe, Zoro, Franky, Usopp, Going Merry, Woop Slap (in Going Merry's figurehead), Kid, Urouge, Bonney, Killer, X Drake and Apoo.
Chapter starts on the 2nd floor of Onigashima castle. We can see someone's shape at the back of the room while many of Kaidou's subordinates start falling down and foaming at their mouths. They look around trying to find who is using the Color of the Supreme King Haki against them. The mystery shape talks.
Mystery shape: "If you come with half-assed resolution,
you won't be able to keep your conciousness while standing before me!!
I am the man who defeated 2 of the Tobiroppo!!
I am Usohachi the Nihou Hunter ("二胞狩りのウソ八" means "Usohachi the 2 of the Flying Six Hunter")!!!"
Kaidou's subordinates: "Eh~~~!!
Two of them!?"
Yes, mystery shape is Usopp that appears riding a giant crocodile (in fact, Usopp is riding a Gifter that has a full crocodile in his head, he hardly can walk).
Nami, Tama and Speed are hiding nearby Usopp. Speed reveals that the Color of the Supreme King Haki is released by Big Mom, who's fighting in other part on the 2nd floor. She's surprised that Big Mom's Haki can affect others on the same floor.
Nami contacts Franky by Den Den Mushi. Franky is in a zone that is connected with the “Live Floor”. He still isn't sure what is happening, but Kaidou's army starts moving toward “Live Floor”. Franky is fighting them alongside Law's crew to stop Kaidou's army from going down.
Cut to the 3rd floor of Onigashima castle, the area where Black Maria and Robin fought is completely on fire. As some Minks watch the scene, we see that Brook is crossing a bridge with Robin in his arms as they run away from fire. Luckily they are both fine, although Robin is still unconscious after her battle.
Brook contacts Jinbe, who is still on the 4th floor of Onigashima castle. There the battle continues against Kaidou's subordinates. Jinbe wonders why Kaidou hasn't returned to the castle and who is stopping him.
We now go to one of the big doors that is connected to the “Live Floor”. Some Kaidou's subordinates try to enter to escape the flames that are in other floors of the castle, but Kawamatsu and the Yazuka leaders fight against them.
Cut to Onigashima's rooftop, Kaidou and Yamato are still fighting. Yamato uses his attack “Narikabura” (Narikabura Arrow) against his father but Kaidou repels it with his kanabo. Kaidou jumps and uses his attack “Kongokabura” (Indestructible Arrow - 金剛鏑) that is a stronger version of “Narikabura”. Yamato stops it but the attack is too strong and finally crash with some rocks.
Yamato recovers from the attack and starts talking to his father.
Yamato: "You always want to kill me!!!"
Kaidou: "Yes, it's true...
This is not just family quarrel.
If you want to call yourself Oden,
then you must be ready to go to war against me!!"
Yamato: "What's wrong with admiring someone!?"
Yamato's flashback begins. Kaidou and Yamato are near the giant Torii at the entrance of Onigashima (it has the dragon that Ace destroys some years later). From Kaidou's appearance, the flahsback takes place shortly after Oden's death 20 years ago, becouse Kaidou still wears the bandages on his chest from the wound that Oden inflicted on him.
Yamato is chained to a wooden column because he keeps calling himself Oden. He is badly injured (he has a big bump on top of his right eye) and he's also hungry. His appearance is the same as the present (same clothes and hairstyle) but being a child. Around him, we can see several of Kaidou's subordinates falling down and foaming at their mouths. Some of them call Yamato “Ogre Princess” (Onihime).
Kaidou: "Color of the Supreme King Haki...
You have potential.
But if you want to keep calling yourself Oden, then you must die Yamato."
Yamato: "Eh~~~!!!"
Kaidou takes Yamato to a cave with the kanji “天” written over the entrance (which has a giant rock for a door). Yamato is chained to a giant rock (that has a shimenawa rope attached to it) while he cries. Inside the cave, there are 3 of Wanokuni's greatest swordmen that Kaidou has captured (for now we only see their silhouettes). Kaidou talks to them.
Kaidou: "If any of you declares your surrender,
I will let you out of this cave and you can join my army. "
As Kaidou says this, he leaves several swords on the ground. He also leaves one portion of food next to them. This way it's possible that they kill each other in order to eat. Yamato begs Kaidou to release him.
Kaidou: "Didn't you say you're “Oden”?
After these words, Kaidou leaves the cave.
Yamato is left alone with the 3 samurai as his stomach growls with hunger. He watches them closely while he thinks he's going to die.
Yamato: "I'm Oden...
But I'm also the son of Kaidou, who killed Oden.
These samurai must hold a big grudge against my father...
And they probably would want to kill me as a revenge!!"
Suddenly, one of the samurai stands up, Yamato believes that his end has already arrived. However the samurai approaches Yamato and gives him the food.
Samuari: "Eat.
A samurai never becomes hungry."
Yamato starts crying thanking him and eats. He can't stop crying even though his mouth is full of food.
Yamato: "I won't forget this rice bowl the rest of my life!!"
When Yamato finished, another of the samurai stands up, draws his sword (which has a black edge), and cuts Yamato's chains easily (like Zoro cut through the rock before taking down Mr. 1 in Arabasta). Yamato starts talking to that samurai and asks his name.
Samuari: "A defeated samurai has no name.
Just call me “Nanigashi” (a certain someone)."
As the samurai speaks we can finally see him clearly, he is identical to Zoro but a few years older. He wears a bandage on his head and on his left eye. In the chapter his name is not said (neither the other 2 samurai's names) but he probably is Shimotsuki Ushimaru, the daimyo of Ringo. The samuari says they sympathize with Yamato and that they loved Oden too.
Yamato shows them Oden's journal, the samuari are shocked. Now we can clearly see the other two samuari. One has a long face with large eyebrows and sideburns, and he also wears a goatee (this is the one that gave rice bowl to Yamato). The other samuari has a triangular-shaped face, a rope tied to his forehead, and makeup similar to Kabuki actors.
Yamato: "I can't read what it says...
Could you teach me to read it?"
The samurai bonds with Yamato, and during the following days they teach him to read. Yamato is amazed and excited with everything that he is discovering. After 10 days, Yamato is weakened and near death because he has no food to eat.
Samurai: "If Kaidou really wants you dead,
then you won't be able to live long enough to see the battle Oden-sama predicted
that will take place within 20 years. "
Yamato: "If I can live until that day...
I will fight for Wanokuni!!"
Shimotsuki Ushimaru?: "Then we will help you to live to join that battle...
20 years is too long for us!!"
The samuari who appears to be Shimotsuki Ushimaru, takes off the top of his kimono and draws his 2 swords. On his back he has a tattoo with 2 crossed swords, the same symbol that Koushirou (Zoro's sensei) uses in his dojo and on his clothes. Then the 3 samurai destroy the giant rock that blocks the cave's entrace and go out to fight Kaidou...
Back to the present.
Yamato: "Tell me...
Why have you taken away my freedom!!?
Why have you taken away this country's freedom!!?"
Kaidou: "You greenhorn!
This world cannot be explained with simple questions and answers!!"
Yamato and Kaidou attack at the same time using the “Raimei Hakke” (Thunder Bagua). Both of them probably have used their Color of the Supreme King Haki becouse the attacks' collision has created an explosion with black lightning bolts.
For the first time, it seems Yamato manages to become equal to his father...
End of chapter, no break next week.