Yuzuru Hiraga's 1928 design for a treaty battleship:
It was initially supposed to replace the Kongo Class but every plan to build them was shelved with the ratification of the London Naval Treaty in 1931.
Without a doubt one of the strangest designs i ever seen, with everything cramped as near as possible in order to shorten the armour belt and save weight to fit into the Washington Treaty limitations.
Her armament consisted in 10 16.1-inch guns (409mm) in two twin turrets and two trple turrets, the latter where unusually the superfiring ones, secondary armament consisted in 16 6-inch guns (152mm) in 4 twin turrets and 8 casemate mounts; finally 4 twin 5-inch AA guns mounted on sponsons abrest the bridge structure completed the picture.
Yuzuru hiraga's 1929 design for a fast battleship armed with 18-inch guns:
Definitely following the steps of her predecessor when it comes to overall appearance and armour setup this massive battleship projected by Hiraga was over 289 meters long (289,5 at the waterline, some 294 overall, 31 meters more than the Yamato class); supposedly capable of 30 knots she featured an all-forward main battery composed of three triple 18-inch (457mm) gun turrets with turret two beign the only superfiring one (much like the british Nelson Class).
Secondary guns where placed all aft, and consisted of three triple 8-inch (203mm) gun turrets, with turret 2 superfiring over the others; AA armament was composed by 5-inch guns (127mm) like the 1928 design, but in addition to the four twin mounts fitted in sponsons near the bridge structure there where two other mounts placed abrast of the funnel, bringing the total count to twelve.
This design eventually developed into the Fujimoto A-140 design, wich in turn evolved into the Yamato class.