Why Yamato handled shells vertically

Why did Yamato's shell elevators handle shells vertically rather than like British and American systems?

The Japanese arrangement sought a smaller break through armour and fitted its preferred shell-storage approach, while British and American systems made the conversion lower down for safety.

A vertical shell route can reduce the size of the opening through protected structure. Large shells also tend to be stored vertically, making that handling path a coherent layout choice. British and American practice favoured conversion lower in the ship because designers judged it safer. The different arrangements reflect distinct assessments of protection, storage, and risk rather than one universally superior method.