Manga Kurogane Pukapuka Tai

The story is about the Unebi, a Japanese commerce raider patrolling the Indian Ocean early in World War II, and its (nearly) all-female crew. Commander Kuki leads the ship with authority and skill. Everyone looks up to her, none moreso than beautiful Executive Officer Mamiya who has constant romantic daydreams about Kuki. Sadly, Kuki is completely unaware of the yuri lust that surrounds her. Kuki also earns the romantic advances of Nina, the commander of an all-female crewed German submarine, and Ann, the aggressively lesbian commander of a British ship.