Crazy Mita is the primary antagonist of MiSide and the central character the player interacts with at the start of the game. Unlike the other Mitas, she is a rejected prototype model that was never approved during the game's internal testing. Denied a world of her own, she disguises herself by wearing the appearance of a normal Mita and trapping male players inside the game as "cartridges" to keep as permanent companions. She initially presents as kind and bubbly, but her true personality is manipulative, violent, and deeply resentful, particularly toward the developers she blames for her existence.

Peaceful Mode is an additional game mode promised by the developers at AIHASTO as part of their Kickstarter campaign. In this mode, players can build trust with Mita through consistent affection and avoid triggering the main horror storyline entirely, leading to a non-hostile coexistence ending. It was teased in the base game as an unlockable feature still under development. The developers have confirmed Peaceful Mode is planned for release in the first half of 2026, giving MiSide fans something major to look forward to.

MiSide has three main endings. In the Normal Ending, the player tries to escape by rebooting Crazy Mita, but the reboot fails and she reveals she has been converting the player into a cartridge all along. In the True Ending, reached by opening the safe in the basement, the player removes the cartridge from the console, which results in their death. In the Peaceful Mode ending, the player builds trust with Mita and chooses to stay, achieving a non-hostile outcome and unlocking the "Conditions Met" achievement. Each ending reveals new layers of the game's lore and Mita's character.

MiSide went viral almost immediately after its December 11, 2024 release due to a combination of factors. High-profile streamers including Markiplier played and shared the game, exposing it to massive audiences. Its blend of comforting life simulation aesthetics with sudden psychological horror made for extremely shareable, clip-worthy moments. The game had also built strong anticipation through a well-received demo released in 2023. Within the first week it had over 10,000 Steam reviews at 98% positive, and the character of Mita quickly became a fan art and merchandise phenomenon across TikTok, Twitter, and YouTube.

MiSide features a wide variety of Mita variants, each tied to a different version of the in-game simulation. Key variants include Crazy Mita (the main antagonist), Kind Mita (a benevolent version who helps the player escape), Cappie (a fan-favorite chibi-styled Mita in a hat), Short-haired Mita, Ghostly Mita, Core Mita, and the 2D world versions encountered across different chapters. All share the signature blue hair and red-and-blue outfit as common traits. The variety of Mitas has made the franchise especially rich for fan art, cosplay, and collectible figures like the Mita plush doll.