Es Mitsurugi is a mysterious and stoic character from the BlazBlue series, first appearing in the visual novel XBlaze and later joining the main game as a playable character. As an Observer, Es possesses unique abilities tied to the Azure and plays a crucial role in overseeing the balance of the Boundary. Her calm demeanor and strong sense of duty often put her at the center of key events, making her an important ally and sometimes a formidable opponent to the protagonists.