The second of the Mogami-class cruisers, the Mikuma (三隈, namesake: Mikuma River) was designed as a heavy cruiser right from the start but, due to restrictions from the London Naval Treaty, the Imperial Japanese Navy mounted turrets with 155 mm guns in order to pass it off as a light cruiser. That the turrets were easy to remove and replace and that there were a number of 20 cm turrets lying around in storage that would perfectly fit into the ships was considered a convenient coincidence.

Mikuma was introduced in Update 1.97 "Viking Fury" purchasable in-game with Golden Eagles. It was included in a premium pack in March 2021, but it was removed from the store after the 9th Anniversary Sale. Compared to her tech-tree counterpart, the Suzuya, Mikuma's only two difference is that she features slightly more crew (958 vs. 918), and that she carries one less scout plane in her visual model (3 vs 4 on Suzuya), although only two can be launched from both ships. As the Mogami-class were built around high top speed and firepower, the Mikuma's lighter armaments result in improved mobility while having the same protection as her heavier-armed sister Mogami.