Following the end of the Boshin War in August 1870, "Kōtetsu" was classified as a third-class warship on 15 November 1871 and was renamed "Azuma" on 7 December. By January 1873, her fighting ability was assessed as low. "Azuma" was assigned to guard Nagasaki during the Saga rebellion in February 1874 and during the Taiwan Expedition of May 1874. On 19 August she ran aground at Kagoshima during a typhoon, but was refloated and repaired at the Yokosuka Naval Arsenal. During the Satsuma Rebellion of 1877, she was assigned to guard duties in the Seto Inland Sea. She was stricken from the navy list on 28 January 1888, and was sold for scrap on 12 December 1889. Her armor plating was reused to make the armature shafts in the electric generators in the Asakusa Thermal Power Station, built in Tokyo in 1895.