is a volcanic Japanese island in the Philippine Sea. The island is administered by Tà Âkyà  and is located approximately northwest of the Miyake-jima and southwest of the Nii-jima. It is one of the Izu Seven Islands, a group of the seven northern islands of the Izu archipelago. Kà Âzushima is administratively part of Kà Âzushima Village (founded 1923), under à Âshima Subprefecture of Tokyo Metropolis. , the island's population was 1,952. Kà Âzushima is within the boundaries of the Fuji-Hakone-Izu National Park.
KÃ Âzu-shima is a compound volcanic island 6 km in length with a maximum width of 4 km. The island is formed from a cluster of eighteen lava domes, with rhyolite and pyroclastic ash deposits. The highest of these lava domes, , has a height of , and was last active in 838 AD per the ancient Japanese history Shoku Nihon KÃ Âki. Compared with most of the other islands in the Izu archipelago, KÃ Âzu-shima is relatively flat, with small eroded hills, and lacks the high coastal cliffs found on the other islands. Earthquake swarms have occurred at KÃ Âzu-shima during the 20th century.
The island has been recognised as an Important Bird Area (IBA) by BirdLife International because it supports populations of Japanese wood pigeons, Tristram's storm petrels, Japanese murrelets, Ijima's leaf-warblers, Pleske's grasshopper warblers and Izu thrushes.
Kà Âzu-shima has been inhabited since at least the Japanese Paleolithic era, and archaeologists have found Jà Âmon period stone tools made from obsidian in Shizuoka and Yamanashi Prefectures. Under the Ritsuryà  system of the early Nara period, the island was part of Suruga Province. It was transferred to Izu Province when Izu separated from Suruga in 680 AD. During the Heian period, obsidian was the primary export from the island.
The island is the hometown of the idol duet Sunny Passion in the franchise Love Live! Superstar!!. Several episodes of the corresponding anime TV series take place there.
In the film Weathering with You, Hodaka Morishima (the male protagonist) is from the island.