Nina Stortebeker is the captain of the all-girl crew of the German Kriegsmarine U-boat U-800, a Type IX-C boat operating in the Indian Ocean against British and Allied shipping in consort with the Imperial Japanese Navy. She is a skilled commander, with sinkings exceeding 100,000 combined tons; this would put her in about the top thirty U-boat commanders of the Second World War.
She's instantly in lust with Commander Kuki after she visits the 'Unebi', and therefore inspires simmering jealousy in Executive Officer Mamiya.
She's always immaculately dressed in Kriegsmarine full dress uniform but with rolled-up sleeves, and her peaked cap turned to the side; however, her personal hygiene leaves much to be desired, partly because there's simply no way to keep clean on a U-boat that has little in the way of washing facilities, but also because she has a fetish for bodily smells. Her stench wakes Gunnery Officer Obama from her sleep, and she proceeds to give Nina a forcible bath and clothes-laundering.
She's a pervert, but, it seems, a honorable one.
Her and Royal Navy Captain Ann have a long history as enemies, which seems to involve both sinking the other at different times, and it seems that they are contestants in love as well.