Onigashima is a region in the Wano Country which was once a peak of Mt. Fuji. After the nation was flooded, it became an island. Emperor Kaidou, all the Stars, and the Numbers were among the Beasts Pirates who used it as their official base of operations. They settled here almost 25 years ago and gave it its name.
Kaisou used his dragon powers to move the island from its location at sea as part of the New Onigashima Project with the goal of relocating it to the Flower Capital. However, the Ninja-Pirate-Mink-Samurai Alliance, made sure that the island landed safely close to the capital.
One Piece Episode 793
Beasts Pirates (former)
The island was not named before Kaidou and the Beasts Pirates settled in Wano Country. Kiadou’s residence was built by Minatomo at some point in the previous 20 years. The castle took nearly five years to be constructed. Ace first met Yamato when he arrived on the island three years earlier to fight Kaidou. He destroyed a statue of a dragon during the fight.
When Joker was defeated, X Drake and a few other Beasts Pirates were outside Kaidou’s hideout on Onigashima, unaware that Kaidou had left for the Ballon Terminal, they tried yelling the news to Kaidou.
Later, when Kaidou had returned to his lair, Scratchmen Apoo called to inform him that they had lost contact with Jack. Kaidou chugged down plenty of alcohol and experienced severe mood swings after realizing his plans to retake Doflamingo had failed. During one of his rages, he even punched some of his followers through the ceiling of his lair.
After the Whole Cake Island Arc, Big Mom called Kaidou and informed him that she would be traveling to Wano to kill Luffy despite Kaidou’s adamant refusal.
Jack received a reprimand from fellow All-Stars King and Queen upon returning to Onigashima for the recent decline in the offerings from the Kuri region.
Kaidou and Big Mom first encountered one another in Onigashima after Queen had taken Big Mom captive. The two fought until they agreed to form an alliance to take over the world. The Numbers and Scratcgmen Apoo returned to Onigashima at this time for the Fire Festival.
The Ninja-Pirate-Mink-Samurai Alliance began their raid on Onigashima on the day of the Fire Festival. When the Straw Hats arrived at the torii, they defeated all of the Beasts Pirates guarding the building. After a brief battle with his old allies, Kanjuro kidnapped Momonosuke after confessing to being a spy for Orochi. He then took a flight to Onigashima to meet with Kaidou and Orochi.
After the rest of the Alliance landed at Onigashima, they divided into smaller groups and traveled in different directions before sneaking into Kaidou’s fortress. The Nine Red Scabbards and Izou reunited after several confrontations (including the Nine Red Scabbards battling the traitor Kurozumi Kanjuro and Luffy dealing with two of the Tobiroppo, Page One and Ulti, before being saved by Yamato).
Later, Kaidou described the New Onigashima Project, in which he would make Wano a pirate state, work with the Big Mom Pirates to recover the Ancient Weapons and the One Piece, and instate Yamato as the new shogun of Wano Country. Kaidou quickly decapitated Orochi after he objected, ultimately breaking their alliance. He then gave the option to join his crew or perish to Orochi’s subordinates. They immediately pledged their devotion to Kaidou.
The Nine Red Scabbards intercepted Kaidou just as he was about to kill Momonosuke. After sustaining minor wounds, Kaidou made the decision to carry the samurais in his flight to the dome's roof. Meanwhile, they were all confronting the gathered Mink Tribe soldiers, who were about to engage in a fierce battle, Jack, Nangi, and some Beasts Pirates also joined Kaidou in the battle.
The Alliance attempted to stop Momonosuke from being executed within the dome. While fighting with King, Sanji was able to free Momonosuke from his chains after Shinobu was unable to save him. After discovering Kaidou was willing to harm his own child, Yamato severed his connection with Kaidou. Luffy begged Yamato to look out for Momonosuke.
Meanwhile, Big Mom was furious with Luffy since he ruined the festival, her tea party, and humiliated her in front of everyone, and she sought vengeance on him. Luffy declared war on Big Mom, Kaidou, and Orochi by saying that he would take them all down.
Big Mom turned her attention to Luffy and struck him with her immense power that damaged a portion of the castle. However, before she could launch another attack, Jinbe and Robin ordered Big Mom to leave the fortress. At the same time, Beasts Pirates and some Numbers gathered in the castle’s centre and engaged in battle with the Straw Hats.
After defeating a few Numbers, Luffy was joined by X Drake, who Who’s-Who had earlier declared to be an opponent of the Beasts Pirates. X Drake requested Luffy let the former join hands with him in the battle, to which Luffy agreed despite his crew's disagreement. Then Luffy decided to ascend to the top of the dome and asked his crew to back him up to ensure that he reached the top of the dome.
Kaidou used his powers to lift the entire island and start moving it to the Flower Capital as the battle continued. In the ensuing battles, Kaidou’s command over the Flame CLouds started to wane, threatening to drop the island and set off the explosives in the Armory by causing the island to crumble.
The island started to fall as Kaidou concentrated all of his efforts on stopping Luffy’s Gomu Gomu no Bajrang Gum. Momonosuke was able to create enough Flame Clouds at the exact moment to capture the island and bring it safely to the ground outside the Flower Capital.
Outside of the front gate, which opens up to the sea and lets ships enter, Onigashima is a mountainous island that is highly challenging to infiltrate. It appears that the waters surrounding the island are filled with whirlpools, making it practically hard to navigate around it without using specialist watercraft like a submarine. Thunderstorms and even blizzards can occur often, occasionally without affecting the rest of the island.
Ships can dock at the port on the island itself. In this port, notable buildings include a massive katana that pierces the earth, water spouters that resemble oni faces, and a huge wagasa embellished with paper lanterns. Two sculptures of kitsune line the port’s entrance, and it looks like a stairwell leads from the port to the Skull Dome’s interior. For those on guard duty, there is at least one lookout point.
Two mountain routes on Onigashima, one to the east and one to the south, can be used to circumnavigate the island around the Skull Dome. A lengthy boardwalk that crosses a huge pond is bordered by wisteria plants, a part of the eastern trail. The broadwalk also leads to areas of the pleasure hall that are built above water in the Left-Brain Tower of the Skull Dome.
A substantial fence built between the mountains blocks the southern route. The Skull Dome’s RIght-Brain Tower can be accessed from the southern gate, while the Left-Brain Tower can be accessed through the pleasure hall entrance.
The Torii is a tiny seaside fort positioned directly in front of Onigashima, and it is topped by a real, enormous torii gate. With many of the crew’s men stationed there, it is heavily armed and acts as the Beasts Pirates’ first line of defense.
It was attacked and destroyed by the Straw Hat Pirates during the Onigashima raid.
The Skull Dome is the primary landmark in Onigashima. Within it is the castle that was home to Kaidou of the Four Emperors.
The Sacred Tree is a massive tree in the southwest that is adorned with a shimenawa. The tree was cut down as a result of Big Mom’s massive attack.
The Sacred Cave was the place where the Beasts Pirates would starve their prisoners. Once it was shut, there was only one vent in the ceiling for communication. Yamato was imprisoned here together with Shimotsuki Ushimaru, Uzuki Tempura, and Fugetsu Omusubi after showing his ability to use Haoshoku Haki. Later, the three samurai cut their way out of the cave.
Listed below are the main inhabitants of Onigashima:
Kaidou, also renowned as the world’s “Strongest Creature,'' was a former Emperor and Governor-General of the Beasts Pirates. He is also Yamato’s father.
Yamato is Kaidou’s son, who was raised to be Kaidou’s heir and was born as his daughter. He grew to have a deep respect for the warrior Kozuki Oden for which the former was imprisoned in Sacred Cave in Onigashima.
King the Conflagration, is one the three All-Stars of the Beasts Pirates and Kaidou’s right-hand man. He was born Alber and belongs to the Red Line’s very extinct lunarian race, which is known for its capability to produce fire.
Queen the Plague, is one of Kaidou’s three closest confidants. He was formerly de facto in charge of Udon, a region in Wano Country.
Jack the Drought is an All-Star of the Beasts and also one of Kaidou’s three closest confidants as the captain of the Mammoth. He used to be regarded as the region’s king in Wano Country’s Kuri.
Who’s-Who is one the Tobiroppo, the top six Shinuchi of the Beasts Pirates. He is also known as the Droplets.
Black Maria is one the Tobiroppo, the top sic Shinuchi of the Beasts Pirates. She runs a brothel in Onigashima, not far from Kaidou’s place.
Bao Huang is a Shinuchi who is a member of the “Marys,” the crew’s surveillance unit, and is a member of the Beasts Pirates. She seems to be in charge of maintaining and delivering the crew’s daily schedules to captain Kaidou.
Onigashima was initially referred to as “Ryugashima,” which translates to “dragon island” rather than “oni island,” in early concept sketches of Franky’s “Franosuke” appearance.
Similar to how the Ninja-Pirate-Mink-Samurai Alliance intends to defeat Kaidou, who was oppressing the people of Wano Country, the island shares its name with an island in the Japanese folktale Momotar, where the titular hero and his animal retainers went to defeat the resident demons that were troubling people.
Onigashimed seemed to be a misty island when it was initially shown in Chapter 793, and the silhouetted skull-shaped mountain was noticeably taller.
Onigashima is a region in the Wano Country.
In the end, three infamous pirates from the Worst Generation, i.e. Monkey D. Luffy, Trafalgar Law, and Eustass Kid–defeated two of the Four Emperors, Kaidou and Big Mom, in what was supposed to be an impossible victory.
The Skull Dome is the primary landmark in Onigashima.