All Comes Down To Timing...

Originally, when a diplomatic mission from Japan visited the U.S. in 1860 (sailing over there on aboard KANRIN-Maru ... which departed from Yokosuka) ----

One of the Japanese objectives was to study the U.S. Navy (and its harbor & shore facilities) and so they were sure to take notice when disembarking at Washington Navy Yard:

A few years later, Japan wanted U.S, to help design & develop the naval base in Yokosuka --- but due to the ongoing North-South Civil War, that was not possible (and the British & Russians could not be trusted) ---- so, Japan was forced to go with "Plan B", and contracted with France to build the Yokosuka Iron Works, which later became Yokosuka Naval Arsenal...