Agent 4

Agent 4 is the one who got recruited by Marie. In the opening of Splatoon 2, a random Inkling wanders toward a manhole and finds Marie waiting alone: her cousin is missing, the Great Zapfish is gone, and her grandfather has wandered off again. Agent 4 gets a Hero Shot, a dryly worried handler, and a job.

Octo Canyon

Over five areas and a fresh set of rebuilt Great Octoweapons, Agent 4 recovers the Canyon's Zapfish, cleans out the Octarian kettles, and uncovers what happened to Callie. The story mode is more elaborate than its predecessor, with weapon-specific challenges supplied by Sheldon and Marie's commentary providing the emotional spine. Agent 4 is the first agent to fight across factory floors and neon districts, and the first to do it with a full arsenal of Hero weapons.

The final battle

The climax puts Agent 4 against the Octobot King with a hypnotized Callie singing from the DJ's side. The turning point belongs to Marie, whose charger shot knocks the Hypnoshades away, but the finish is Agent 4's, delivered to the sound of the reunited Squid Sisters performing the Calamari Inkantation. Octavio goes back in his globe. The Zapfish goes home. The Sisters are whole again.

The quiet one

Agent 4 is the agent the later games talk about least. They do not appear in the Octo Expansion, and in Splatoon 3 Marie mentions only that they are off somewhere doing their own thing. Fans have theories, most of them fond: that Agent 4 stayed close to the Squid Sisters, or joined Grizzco, or simply went back to Turf War. The games leave it open.

Legacy

If Agent 3 is the legend, Agent 4 is the one who fixed a family. Their contribution to the series is not a rescued city but a rescued cousin, and the Squid Sisters' return in Splatoon 3, as Agents 1 and 2, is a direct consequence of their work in Octo Canyon.