Although it is very common to consider the Hiryu aircraft carrier as the twin ship of the Soryu, there are so many differences between them that two totally different classes can be considered. In Hiryu it was decided to install the small command tower on the port side of the flight deck, a unique arrangement that would only be shared with the Akagi aircraft carrier. The Hiryu displaced some 1,400 tons more than Soryu and had a different number of 25mm AA guns placed in a different way. The flight deck was one meter wider and the hangars were longer but less tall. Another remarkable difference was the level of protection, higher in the Hiryu. The horizontal protection was the same, but the armoured belt was increased up to 89mm across the machinery and up to 150mm along the magazines. Hiryu entered service in 1939 and participated in the Pearl Harbor’s attack. During the Battle of Midway it was attacked by 16 Marines ground based aircrafts and managed to shoot down 8. Later, Hiryu launch their aircrafts against the USS Yorktown aircraft carrier, which resulted disabled after the attack. In another stage of the battle it was attacked by USS Enterprise‘s aircrafts, resulting in serious damage. Finally on June 5, 1942 Hiryu was abandoned and was sunk by its own escorts.
HIRYU gallery and more info