Why the Ibuki class straddles cruiser categories

Were the Ibuki-class ships armoured cruisers or battlecruisers?

They were built as armoured cruisers, but their size and armament encouraged later battlecruiser classification. In this assessment, they were forerunners of the large cruiser.

The Ibuki class was built as an armoured cruiser. At nearly 15,000 tons normal displacement, with four 12-inch guns and eight 8-inch guns, it was much more powerful than likely cruiser opponents. Its speed and fighting power later encouraged battlecruiser classification. Prestige and the treatment of tonnage under naval treaties may also have favoured that label. The comparison with the Alaska class places Ibuki on the path toward the later large cruiser, below a true capital ship.