Aoi-ku is one of three wards of the city of Shizuoka in Shizuoka Prefecture, Japan, located in the northern part of the city. Aoi-ku borders Suruga-ku in the south and Shimizu-ku to the southeast; the west faces Shimada, Fujieda and Kawanehon and its northern tip extends into the border between Nagano Prefecture and Yamanashi Prefecture. It is the largest ward in Japan in terms of geographic area.