A Chinese submarine success could redirect Japanese ASW research

What changes if China buys submarines and sinks a major Japanese warship in 1937?

Japan would give antisubmarine warfare greater priority, though limited specialist teams mean that effort must come at the expense of another research program.

The Imperial Japanese Navy already possessed hydrophones, escorts, and an anti-submarine doctrine, so the loss would accelerate an existing field rather than create it. Japan's small pool of technical teams forces leaders to redirect people and money from another programme. A capital-ship loss might encourage a search for British detection technology and create pressure to publicise new battleships such as the Yamato class. Germany and Italy would be more likely to revisit destroyer numbers and anti-submarine equipment than to discover the submarine's potential from scratch. Submarines had already sunk major warships during World War I.