Hoping that they could get a break at Sarah's (Agent 3) old house away from the city, a sudden news flash changed everything... Inkopolis, Sarah and Mike's (Agent 8) home, as well as every other inkling's, has been invaded by the Octarian Army! In an effort to help save their beloved city, the pair quickly rush back to Inkopolis! Though neither know what the future has in store for them..!

Mike (Agent 8) has finally got used to life up on the surface. Alongside with his girlfriend and best friend in one, Sarah (Agent 3), he feels like he can overcome any challenge or obstacle for her sake. After a series of unfortunate events, it's up to the Splatoon to bring back their beloved agent.

After going through the grueling missions in the Deepsea Metro, Agent 8 (Mike) finally makes it to the "Promised Land." He then finds himself facing discrimination for being an Octoling. Agent 8 finds by coincidence Agent 3 (Sarah), who provides him with a place to stay until he was able to get on his feet again. The duo slowly start to fall in love with each other, but stop themselves from doing so. After all, everyone will disapprove of their relationship.