The Anime Lad
Lieutenant Ledo has known humanity through an interstellar war against the Hideauze. A spatial distortion strands him and his humanoid weapon Chamber on Earth, a lost planet now covered by ocean. People survive aboard enormous linked fleets such as Gargantia. Ledo's combat specialization is not a complete civilian skill set.
Super Eyepatch Fox
Fight in deep space. Fall through a distortion. Wake on a flooded Earth where communities live aboard giant fleets. Ledo and Chamber arrive with military skills but no understanding of local history or culture. Gargantia begins by replacing endless war with unfamiliar civilian survival at close range.
Gigguku
Ledo drops out of a distant space war and lands on an ocean world full of people living aboard connected ships. He understands combat and almost nothing about their culture. That contrast is fantastic. Every ordinary day on Gargantia challenges the idea that survival must look like military service.
Father's Basement
The military prologue presents its conflict in broad terms, and the proper nouns arrive before much human context. Earth improves the setup. Ledo possesses a powerful combat machine but lacks knowledge of the flooded planet's culture, making adjustment as important as physical survival. That tension starts immediately.