In a completed Eight-Eight Fleet, Number 13 would join Nagato and Tosa in the battle line while Kii supported Amagi's faster arm. Its eight 18-inch guns show that Japan was already exploring very large-gun capital ships. Yamato's later nine-gun, 18.1-inch battery therefore had a clear design precedent, even though Yamato accepted a lower speed. Cancelled programmes can leave research, industrial knowledge, and design assumptions that reappear in later generations. The parallel British discussion makes the same point about weapon development continuing after individual projects change or disappear.
Notable Point · 26:28-29:07
Number 13 as a bridge toward Yamato
Number 13 belongs in the battle line with Nagato and Tosa, while its 18-inch battery makes Yamato's later armament less surprising.