The Shinkaisei-kan version of aircraft in Kantai Collection. Unlike the shipgirl aircraft, which tend to be miniature replicas of real World War II-era Imperial Japanese Navy aircraft, Shinkaisei-kan aircraft have the alien appearance of the Shinkaisei-kan.
They usually look triangular from the top, with a black metal skull-like appearance. Underneath, they have cannons sticking out of their "mouths" or have bombs or torpedoes strapped underneath. Some, notably those launched by Northern Ocean Hime, have a more "takoyaki"-like spherical look, and are white with red highlights.
Not to be confused with the spherical and eyeless Floating Fortress or Escort Fortress.