was a after Kyōtoku and before Chōroku. This period spanned the years from July 1455 through September 1457. The reigning emperor was .
Change of Era
- 1455 : The era name was changed to mark an event or a number of events.
Events of the Kōshō era
- 1456 (Kōshō 2, 3rd month): Ashikaga Yoshimasa visited Iwashimizu Shrine; and all the officials of the Daijō-kan joined him in going there.
- 1456 (Kōshō 2, 8th month): The father of Emperor Go-Hanazono, Fushimi-no-miya-shinnō Sadafusa, died at age 85.