What prewar 40 mm Bofors adoption gives Japan

What if the Imperial Japanese Navy adopted the 40 mm Bofors before the Second World War?

Its ships would defend themselves better and suffer fewer losses, provided Japan built the support system, but the change would not reverse the war's outcome.

Replacing Japanese 25 mm weapons with 40 mm Bofors guns would improve shipboard air defense in this counterfactual. Japan would first need the manufacturing capacity and infrastructure to support the new weapon. With that system in place, some individual engagements and ship losses would change. The improved defensive performance is still judged insufficient to reverse the overall outcome of the war.