Three weeks after the incident that left Captain Napolipolita’s ship perched on top of Graviton City, A‑Ko and her friends head off on a summer vacation. While A‑Ko contemplates shedding some weight, B‑Ko devises a new plan to defeat her red‑haired rival and win over C‑Ko. Meanwhile, Napolipolita and Spy‑D suffer intense homesickness, pleading for a way to return to their home planet. At the same time, Hikari Daitokuji, B‑Ko’s father and CEO of the Daitokuji Financial Group, provides the local military with new mecha, preparing to attack Napolipolita’s ship and seize its advanced technology.