I really don't get this design. The Mogami was notorious for being topheavy, so wouldn't it be obvious for the personification to have large breasts?
The Mogami class were laid down as light cruisers and used a lot of weight-saving methods (lighter materials, welded construction, etc.) to keep their displacement low. Displacement seems a rough analogue for breast size in KanColle, though different artists seem to take this to different degrees.