Myōkō (妙高) was the lead ship of the four-member Myōkō class of heavy cruisers of the Imperial Japanese Navy (IJN), which were active in World War II.^[2] She was named after Mount Myōkō in Niigata Prefecture. The other ships of the class were Nachi, Ashigara, and Haguro. Myōkō was approved under the 1922-1929 Fleet Modernization Program as the first heavy cruiser to be built by Japan within the design constraints imposed by the Washington Naval Treaty, and was the first of the "10,000 ton" cruisers built by any nation.^[3] Naval architect Vice-admiral Yuzuru Hiraga was able to keep the design from becoming dangerously top-heavy in its early years by continually rejecting demands from the Imperial Japanese Navy General Staff for additional equipment to the upper decks. However, during modifications and rebuildings in the 1930s, the final displacement rose to 15,933 tons, well over the treaty limits.^[4]