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.