Japanese treaty battleships and the road to Yamato

Japan gains authority to build three modern fast battleships and has a record of concentrating resources on capital ships even when other programs suffer. Several gun arrangements are possible, including designs whose turrets might later accept larger weapons, but the infrastructure benefit matters more than any single speculative layout. The yards, machinery, and support systems built for these ships become a funded rehearsal for Yamato and Musashi rather than requiring one abrupt expansion in the late 1930s. Treaty authorization therefore turns an immediate 16-inch program into preparation for the later 18-inch fleet. Larger cruiser and carrier allowances could broaden the rest of the navy as well, although the exact construction mix remains uncertain.