Koka (甲賀市, -shi) is a city located in the southern part of Shiga, Japan.
As of 2004, the town has an estimated population of 93,418 and a density of 193.93 persons per kmē. The total area is 481.69 kmē. The city was founded on October 1, 2004 when the town of Koka, Minakuchi, Shigaraki, Tsuchiyama, and Konan to form one new city.
Shiga was known as Omi Province before the prefectural system was established.
Shiga shares a border with Fukui Prefecture in the north, Gifu Prefecture in the east, Mie Prefecture in the southeast, and Kyoto Prefecture in the west.
Shiga District was dissolved as a result of this merger.