In order to service new and larger aircraft like the Nakajima B6N "Jill" torpedo bomber and the Yokosuka D4Y "Judy" dive bomber, the flight deck was extended over at each end to a total length of from 27 March to 26 April 1944. "Hōshō" also received new arresting gear and a new crash barrier. The additional weight high up in the ship adversely affected her stability and she was restricted from operations in bad weather lest she capsize. At some point during the war the ship's 14 cm guns were removed and she received about twenty 25-millimeter Type 96 autocannons in single mounts. They fired projectiles at a muzzle velocity of ; at 50°, this provided a maximum range of , and an effective ceiling of . The 15-round magazines needed to be changed frequently, and the maximum effective rate of fire was only between 110 and 120 rounds per minute.