In Erina and the City of Machines, Erina, an ambitious engineer, and self-styled adventurer, lands in the city of Era Sheila after journeying from one location to another, taking on various tasks in her idealized dream of adventure. Named after a legendary explorer whom Erina admires, Era Sheila holds a special significance for her. However, she soon discovers that this city has a lesser-known nickname: the City of Machines. As Erina delves deeper into this metropolis teeming with lustful men, she wonders what challenges and experiences await her in this enigmatic place.