The Myôkô class was the first of the 10,000 ton cruisers designed by Vice Admiral Y. Hiraga. They were a part of the 1923 - 1929 Program. These cruisers were still limited by the Washington Treaty, though in the end they exceeded the limits. The design for the Myôkô class was approved in August 1923. His design had no fixed torpedo mounts, but when Hiraga sent overseas the Naval General Staff had his replacement added the fixed mounts back into the design.
The four ships of the Myôkô class were ordered in the 1923 New Reinforcement Program.
There's one catapult for the two aircraft carried.
Initially the E2N1 floatplane was carried. This was later changed to E8N1 and E7K1 floatplanes. Just before the war started this was updated to one E13A1 "Jake" and two F1M2 "Petes".
There was an arched bulkhead inside the main belt to help with protection against torpedoes.
There were eight / nine boiler rooms for the twelve Kanpon boilers.