Splatoon 3's developers have revealed that the game takes place in 2022 and that "the same amount of time has passed in the squid world as the real world".
Today marks the release of Splatoon 3 and to celebrate that fact, several of the developers who worked on the game have taken part in an "Ask the Developers" interview with Nintendo, discussing some interesting background information about the game, as well as how some gameplay mechanics and features were decided upon.
One of the more interesting discussions is in regard to the passage of time and that Splatoon 3 actually takes place in 2022. Splatoon fans will have noticed that characters from the first game have aged since then and that Splatoon's setting is constantly shifting to reflect changes in the world itself. This is obviously something that most Nintendo games don't tend to follow, with game and art director Seita Inoue even pointing it out as "unusual".
On the topic, Inoue said, "It is also the year 2022 in the Inkling world. In many other games, for example, the characters do not age even if time passes in the real world, or time moves forward in the game regardless of the time in the real world. But in Splatoon 1, 2, and 3, the same amount of time has passed in the squid world as in the real world. Therefore, the characters grow, and cities and cultures develop over time."
Splatoon's producer, Hisashi Nogami commented on why he thought this was important for Splatoon to follow. He said, "We wanted players to feel that the time in the game passes with their own real lives. In that sense, we could say that this is a game franchise in which players and developers walked side by side over the seven years since the first release. In terms of design, we were conscious that the game is set in modern times, and we depicted the world based on street culture."
Examples of the passage of time can be seen all throughout Splatoon 2 and Splatoon 3. Not only do characters like Cuttlefish, Lil' Judd, and Murch all age in-between games, but events within each campaign also stick around, such as your character from the first Splatoon becoming the captain of the Squidbeak Splatoon by this game.