The new Japanese ships are described as large destroyers rather than cruisers. Their size follows the mission: they take over an air-and-missile-defence role once assigned to land-based Aegis Ashore. Classifying them by displacement alone would miss the system and purpose driving the design.
Notable Point · 3:36:26-3:36:46
Japan's large destroyers replace Aegis Ashore
A short modern-design answer explains the size of Japan's new destroyers through the Aegis Ashore mission they are meant to replace.