Type 5 offered Yamato better anti-aircraft defence

How effective might the Japanese 40 mm Type 5 have been on Yamato?

It would probably be far better than the 25 mm Type 96 battery it replaced.

The Type 96 25 mm weapon provides an unsatisfactory baseline for the comparison. Almost any alternative would improve on that battery, and the Japanese 40 mm Type 5 would serve Yamato much better. This is a relative judgement between the two weapons rather than a detailed performance estimate for the Type 5. No exact effectiveness figure is assigned.