Two battleships (Yamato and Musashi)

Four Yamato-class Battleships were ordered. Two of which were completed. (Yamato & Musashi). The third (Shinano) was partially-completed, and then converted into an aircraft carrier. The fourth was cancelled and never built.

Mushashi and Yamato

There were to be 3 super battleships built in Japan during WW2; Yamato, Musashi, and the Shinino. After the Battle of Midway aircrew losses, the Imperial Navy decided they needed more carriers and NOT more battleships, consequently, they converted the last of the YAMATO class battleships into an aircraft carrier. The largest Aircraft Carrier of WW2, the IJN Shinino, which was built on a YAMATO battleship class hull, was sunk by a USN submarine.

The Yamato and Musashi were Yamato Class battleships that each had 18.1 inch naval guns as their main armament ~ see related link below to additional information .