Why Japan calls helicopter carriers destroyers

Why does Japan call helicopter-carrying flat tops destroyers instead of carriers?

The label helps avoid the political and constitutional implications of openly operating aircraft carriers while retaining similar aviation capability.

Japan is not supposed to operate conventional offensive aircraft carriers under its postwar self-defence framing, so terminology carries political weight. Calling a flat-topped aviation ship a helicopter destroyer avoids openly presenting it as the prohibited category. The practice resembles the British use of labels such as through-deck cruiser for ships that performed carrier-like work. The name does not erase the aviation capability, but it makes that capability easier to fit within a sensitive legal and political vocabulary.