Onigashima

Onigashima is an island located somewhere in the New World. Kaido of the Yonko resides here.

Geography
Onigashima appears to be a Winter Island, with snow constantly falling. The landscape is dotted with trees.

Kaido's Residence
Kaido resides in a giant cave that resembles a skull with long horns on top. This cave occupies a considerable portion of the island.

Dressrosa Arc
X Drake and some other Beasts Pirates were outside Kaido's lair on Onigashima when they received news of Doflamingo's defeat, which they tried shouting out to Kaido.

Zou Arc
After hearing the news about Doflamingo's defeat, 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.

Reverie Arc
Kaido received a call from Big Mom, who told him she would be coming to his territory to kill Luffy despite his adamant refusal.