“Bullied, abused and ignored, Mishima is an isolated individual who craves freedom from his day-to-day tortures. He used to be one of the students that Kamoshida likes to abuse and harass the most and often uses him to spread unfavorable rumors to students that he dislikes against his own will. Initially nervous and scared because of Kamoshida's abuse, once the tyrant of Shujin was neutralized, his excitable and loyal nature undoubtedly shines through. While his enthusiasm can become annoying, at times Mishima will still be hesitant and respectful, often apologizing for texting when he is sure the protagonist is busy. Mishima idolizes the protagonist as a cool superhero, most likely viewing the protagonist as his "savior" from his abuse under Kamoshida.” - Persona 5 Wiki

Voice Example

https://www.youtube.com/watch?v=bAJJ6Fu_QQY