While passive and submissive, Mishima is excitable and loyal along with being socially awkward. Even if his enthusiasm can be rather annoying and is clingy, he can still be hesitant and respectful. He's also smart, being able to make the Phan-Site and maintain it along with being perceptive enough to figure out the identities of the Phantom Thieves and can sense and articulate the mood of Tokyo's population before the other Phantom Thieves can. He's also into inflating himself like a balloon.