Onigashima

Onigashima is a New World island and a region of Wano Country, which serves as the official base of operations for the Beasts Pirates, including the Yonko Kaido, the All-Stars, and the Numbers. Onigashima is a mountainous island that is very difficult to access outside the front gate, which connects directly to the sea, allowing ships to sail in. The waters surrounding the island are apparently lined with whirlpools that make navigating around it nearly impossible unless one utilizes specialized watercraft like a submarine. The island itself has a port where ships can dock. Notable structures in this port include a gigantic katana piercing the ground, water spouters that resemble oni faces, an enormous wagasa decorated with paper lanterns. The entrance to the port is lined with two statues depicting kitsune and a stairwell appears to connect the port to the interior of the central skull-shaped mountain. The torii is a small fortress located at sea, right in front of Onigashima.

It is heavily armed and serves as the first line of defense of the Beasts Pirates, having a number of the crew's soldiers stationed there.  The most notable landmark of Onigashima is a large rock formation resembling a skull with horns. This mountain appears to have multiple rectangular rocks on and around it, and is easily visible from a great distance. Based on the mansion's location, the skull's interior has a winter climate. Kaido resides in a giant mansion inside the skull-shaped mountain. Although it has yet to be shown in full, the mansion appears to occupy a considerable portion of the island's interior, being large enough to house the abnormally large top ranking members of the Beasts Pirates. Inside the mansion is a cell which was once occupied by Eustass Kid. According to the blueprints Kin'emon acquired from Ashura Doji, the mansion has a rear entrance accessible only from the back of the skull-shaped mountain.  According to Kin'emon, Minatomo built Kaido's residence.

X Drake and some other Beasts Pirates were outside Kaido's lair on Onigashima when they received news of Joker's defeat, which they tried shouting out to Kaido, unaware that he had gone to the Ballon Terminal. Sometime later, Kaido returned to his lair and received a call from Scratchmen Apoo, telling him they lost contact with Jack. Realizing his plans to take back Doflamingo had failed, Kaido drank a lot and suffered from intense mood swings, including a rage that caused him to hit some of his subordinates through the roof of his lair. Kaido received a call from Big Mom, who told him she would be coming to his territory to kill Luffy despite his adamant refusal. Back at Onigashima, Jack was scolded by fellow All-Stars King and Queen because the offerings from the Kuri region had been decreasing lately. After Queen captured Big Mom and brought her to Onigashima, Kaido and Big Mom met face to face and the two clashed until they decided to form an alliance to conquer the world. Around this time, the Numbers also return alongside Scratchmen Apoo to Onigashima for the Fire Festival. On the day of the Fire Festival, the Ninja-Pirate-Mink-Samurai Alliance commenced the raid on Onigashima. The Straw Hats reached the torii and defeated all the Beasts Pirates members stationed there.

Udon

Udon is a region located at the southeast of Wano Country currently under the rule of the All-Star Queen of the Beasts Pirates. It is an industrialized region of weapon factories where the lower-class are forced to work to exhaustion and death. Udon is mostly a wasteland with weapon factories where the workforce is mostly prisoners as slave labor to the point of death. Before Kaido's occupation of the country, Udon was covered in a thick forest. However, this forest was burned down during a fight between the Beasts Pirates and Kozuki Oden and his retainers. Tokage Port is Udon's port and one of six in Wano. It was set to be the backup meeting place for the Ninja-Pirate-Mink-Samurai Alliance. On the night before their planned attack, the port was seemingly attacked and was left in ruins. The port's name contains the kanji for "eternal" and "shadow". Tokage is also the Japanese word for "lizard", thus the port is represented as a lizard.

Twenty years ago, after Kozuki Oden lost his patience with Orochi's heinous acts, he gathered his retainers to take him down. Their first stop was Onigashima, where they planned on taking out Kaido, but they were confronted by him and his crew on the way. Unwilling to stand back, Oden launched forward, attacking the massive army with his retainers. While Oden charged at Kaido, the Scabbards fought off the crew, who outnumbered them a hundred to one. After a fierce battle, during which the untouchable Kaido suffered a grave injury, Kurozumi Higurashi transformed into Oden's son, Momonosuke, and distracted Oden long enough for Kaido to strike him from behind. Soon after Oden and his retainers fell, they were imprisoned in the Flower Capital. Sometime during the battle, a fire broke out and set the forest that was the battleground aflame for five days before the rain put it out. As the Beasts Pirates took over Wano Country and Orochi rose to power, Udon was converted into a series of weapon factories which served as a labor camp, where all of Orochi's dissidents who openly rebelled against him are imprisoned and sentenced to harsh penal labor for life. Among them are the Yakuza bosses, including Hyogoro the most influential Yakuza himself. Thirteen years ago, Kawamatsu was captured and imprisoned here. Unlike his fellow prisoners, Kawamatsu was not sentenced to harsh labor and was simply tightly tied up in his cell due to his immense fighting prowess which was deemed a significant threat.

The Beasts Pirates tried to weaken Kawamatsu into submission by feeding him poisoned fish daily but to no avail. Eustass Kid and Monkey D. Luffy were later imprisoned in Udon. Raizo infiltrated Udon to liberate Luffy and coincidentally discovered Kawamatsu in his cell. After recruiting Caribou whose Numa Numa no Mi was a useful asset, Raizo secretly approached Hyogoro and informed the latter of the upcoming revolution planned by Kin'emon. Extremely happy to learn that the Kozuki Revolution was still possible with the Nine Red Scabbards and Kozuki Momonosuke being alive, Hyogoro explained to Raizo of the immense numbers of potential allies they could gain by recruiting all his fellow prisoners. Later, at Tama's idea, an amnesiac Big Mom was manipulated into invading Udon much to the shock of Queen and the Beast Pirates stationed in Udon. As Caribou cut off Udon's communications, Big Mom rampaged in Udon in search of Oshiruko. She was later subdued and personally escorted by Queen to Onigashima, leaving behind a liberated Luffy who managed to convince all of Udon's prisoners to rise up and fight against the oppression of the Beast Pirates. After Udon was conquered and turned into a base of operation for the Kozuki Family's revolution, Tama tamed Babanuki and had him give a false report to Queen to avoid any suspicion. Over the next couple of days, while the liberated prisoners prepare for the strike against the Beasts Pirates, Luffy used the time and space to train and master his new technique. On the day of the Fire Festival, Momonosuke's group reached Tokage Port to find it in ruins, and their allies missing. This was the result of Orochi's plan to foil their plot, and destroyed all access to Udon.