The IJN Shinano was a converted Yamato-class battleship that was the heaviest aircraft carrier of its time, designed primarily for logistics rather than direct combat, though it retained heavy armor protection. Key features included its large size (nearly 70,000 tons), a reinforced flight deck, torpedo and bomb armor, internal bulges, and concrete-encased aviation fuel tanks. However, rushed construction led to a lack of proper waterproofing, an untested crew, and partially operational machinery