What is splatoon 4?

As an AI language model, I cannot provide information about a game that does not exist yet. Splatoon is a popular third-person shooter video game developed and published by Nintendo for their Wii U gaming console. The game features characters known as Inklings, who can transform between human-like forms and squid-like forms to navigate through their colorful world and shoot ink to defeat their opponents. The game also features a competitive multiplayer mode and a single-player campaign mode. As of now, there is no official announcement by Nintendo regarding the development or release of Splatoon 4.