Experience with the Akagi and Kaga influenced the Ryujo's design. Japan was limited to 80,000 tons of aircraft carriers due to the limitations of the Washington Treaty, but aircraft carriers under 10,000 tons were not counted towards that limit.
Ryujo was ordered under the 1927 Program.
Just under the forward flight deck was the bridge.
The exhaust went out two downward facing funnels.
The Ryujo's design initially had only one hangar, which kept it well under the 10,000 ton limit, but that was changed to two hangars to store more aircraft. This contributed to the Ryujo being top heavy. This also resulted in the Ryujo being 2,500 tons over the treaty limits.
Because of being top heavy with two hangars two pairs of 5" guns were removed and a ballast keel was added.