Koka

Koka is a term that can refer to several distinct subjects, most commonly in Japan. In historical geography, Kōka (甲賀) designates a region in what is now Shiga Prefecture on the island of Honshu. The area includes the city of Kōka (Kōka-shi), established in 2004. In popular culture and folklore, the Kōka region is linked with ninjutsu legends, alongside the neighboring Iga region.

In a different sense, Kōka also denotes a Japanese era name (nengō): Kōka, written 弘化, which lasted from 1844 to 1848 during the late Edo period. Era names were used to mark periods and official dating of events, and Kōka followed the Tenpō era and was followed by An’ei.

Beyond Japan, Koka is also used as a personal name or surname in various cultures, and may appear in place names elsewhere. Spelling variants include Kōka, Koka, or Koga in some romanizations; diacritics are frequently omitted in English-language texts.