ODa was an assistant to the author of rurouni kenshin .
The author was Nobuhiro Watsuki and one of his assistant was Eichiiro Oda.
Sometimes it goes unnoticed but Oda takes inspiration from Kenshin almost just as much as from Draonball, still Kenshin is a much lesser known manga, thus many little things goes unnoticed.
Near the beginning of the Jinchuu Arc of Rurouni Kenshin, Enishi tells Kenshin that he has ten large battleships (of the type deployed by Shishio in the previous arc) and threatens to use them to burn Tokyo to the ground if Kenshin backs out of their upcoming confrontation.
Now compare this with the infamous Buster Call
from One Piece, which is virtually the same thing.
It’s also entirely possible that this was intentional since Eiichiro Oda, author of One Piece, used to be Watsuki’s assistant before starting his own series.
rurouni kenshin took place during the meiji restoration which kenshins actions worked towards etc. and one of the things that led to the meiji restoration was opening japans borders and odens wish was to open the borders of wano country which represents japan(
The name is a pun, as “Wa no Kuni (和の国
? literally meaning “Country of Harmony”)“ is used as a name for Japan.The fact that the swordsmen in this country are called "samurai” and its closed-door policy are also a reference to Japan in their Feudal era.)
opforum.net/threads/some-potential-insights-about-a-wano-arc.54085/
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The Edo Period’s transition into the Meiji.
Without going into too much historical detail, here’s the jist of things. For hundreds (if not over a thousand) years Japan had remained completely isolated from the world, purposely. It defended its borders against the Chinese and the Mongols on a couple occasions, and became the isolated country that Oda seems to have alluded to within the One Piece world. There was a distinct pride about retaining Japanese as separate from the world.
For roughly 200 years Japan was within the “Edo Period” which was ruled by the Shoguns. Specifically, the Tokugawa Shogunate. Shoguns were de facto military leaders that ruled over the
daimyo (or feudal lords) and had power that was more material than the Emperor, who was just a figure head essentially. At the end of the era, there became a wave of change between the Shogunate and the Imperialists. The Imperialists were those who wanted to establish a new government, do away with the Feudal System, open its borders, and begin to interact with the world.
Thus the period of the Bakumatsu began. It was a war between the shogun’s army and the Imperialist Army. This civil war ended with the fall of the Shogun, and the Meiji Period then began. This new Meiji Era would be led by a single Emperor and the nation itself opened its ports to trade, commerce, and outside influence that would change the technology, habits, clothing, and lifestyle of the Japanese themselves.
The Isshin Shishi were the forces that fought to open the borders
As for the Imperials that helped to overthrow the Shogun, they were called the Imperialists and had a group known as the Ishin Shishi under them. Kenshin served the Ishin Shishi (and fought against the Shinsengumi, whom Saito was a member of, ). “
kenshin.wikia.com/wiki/Category:Ishin_Shishi
and kenshin himura was part of the ishin shishi
opforum.net/threads/chapter…iction-of-how-wanos-arc-might-be-setup.48759/
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Meiji Restoration Period in Japan:
The Meiji Restoration (明治維新 Meiji Ishin?), was a chain of events that restored practical imperial rule to Japan in 1868 under Emperor Meiji. The foundation of this was through an "Alliance” between two leaders( from Chōshū and Satsuma domains) and this alliance happened because of an historical figure called…wait for it….Ryōma often regarded as the “father of the Imperial Japanese Navy” (I do know our guy is called Ryūma but there must be some implication here by Oda, right?).“
and the bakumatsu
https://en.wikipedia.org/wiki/Bakumatsu
it was basically a fight between the shogun side and the emperors side and the enemy in wano includes the shogun momonosuke means peach emperor
zoro has repeatedly stated in the series that he has wanted a fire sword and then kinemon has shown up with the fire sword technique and ability to cut fire
in rurouni kenshin shishio had a sword that was made in such a way that it could be called a fire sword and use fire techniques like combining a cut and flame or a fire tornado etc so the character who was based on shishio would also be able to use fire sword techniques and cut fire and be a better
and the futae no kiwami from kenshin sounds like one pieces hasshoken
kenshin.wikia.com/wiki/Futae_no_Kiwami
The Futae no Kiwami is a technique that focuses on allowing the full use of one’s strength and power to be fully utilized at its maximum output. Though its utilization can be used with all of the body, the use of it through extremities, especially the fist, is often the first part to start with when to be studied and mastered.
The Futae no Kiwami’s principle aspects come from understanding that all matter bears a level of resistance, and that a single blow’s impact is wasted upon meeting this resistance. From this, two blows are to be acted to fully transfer this impact. With the fist, the first blow, using the proximal interphalangeal joints of the hand, meets to absorb the object’s initial resistance. Then, with folding the hand immediately to switch over to the proximal phalanx knuckles, delivers the final strike to the weakened object; in addition, the two hits are to be delivered at nearly the same time, with a few milliseconds interval. The result is the complete destruction of the object, which has no more resistance to sustain itself and collapses into dust.
the futae no kiwami is a vibration attack which can produce shock waves from the double hit. just like how hasshoken is a vibration attack
onepiece.wikia.com/wiki/Hasshoken
this fighting style allows the user to control vibrations around their limbs to generate shock waves . This shockwave is powerful enough to destroy a metal shield or defeat a strong man easily.
Sai also claimed that these attacks are unblockable and reverberating, causing defenses to shatter
and given that sai knows it its quite possible that sanji can learn hasshoken in a reference to how sanosuke one of kenshins main group learn futae no kiwami ( and he can only do it in his arms ( well arm in his case) and is mainly a fist fighter sanji will only use hasshoken in his legs
and sanji had a habit of facing off against opponents with high defensive capabilities/defensive oriented fighters (or martial artists ) like pearl, jabura with his Tekkai Kenpo, a technique which allows him to move while using Tekkai, and throw powerful punches at his enemies while maintaining his defense, wanze with his ramen kenpo, and absalom with his modified body they all boasted of his awesomeness of their defensive capability but sanji broke through, and I am sure that oda would want his martial artist crew to become the ultimate defensive breaker in crew so it fits for Sanji to learn Hasshoken, another technique with vibrations that is used to penetrate defenses and armour and what not.
and he can combine hasshoken with diable jambe to form an even stronger attack and more fire