A Fletcher derivative gave postwar Japan a familiar destroyer baseline

Why was a modified Fletcher initially proposed for what became the 1959 Akizuki class?

It was a familiar and credible baseline while Japan worked out the requirements for its own postwar destroyer.

Postwar Japanese designers needed a credible baseline while working out what their new destroyer should do. A modified Fletcher was familiar because Japanese forces had experience operating alongside ships of that type. It was therefore a reasonable point of departure even though the final Akizuki class would become its own design. Inherited operating experience can shape early concept work without dictating the final ship.