What would Yamato look like in a world with G3 and N3?

What would Yamato have been like in a world where the British G3 and N3 classes entered service?

The historical Yamato would have been only an entry-level response; Japan would probably have pursued something larger, especially if a later treaty normalized roughly 45,000-ton ships and 18-inch guns.

In this counterfactual, the Yamato known from history would not simply appear unchanged in an N3 world. A British 18-inch-gunned battleship already in service would make Yamato an entry-level reply, pushing Japan toward a larger design rather than a copy of the historical ship. If negotiations were delayed until about 1925, the completed G3 and N3 classes could have raised a treaty ceiling toward 45,000 tons and 18-inch armament. Britain had also considered 18-inch guns for G3, which would have intensified the pressure further. The watch point concerns procurement benchmarks rather than claiming that a specific larger Japanese design was certain.