Mirio is a tall young man with a very muscular build and several noticeable scars around his lower arms. He was born on July 15th. He has blond hair, the top part of which is arranged in a quiff hairstyle, while the bottom section is worn swept backward. Mirio usually comes across as a highly goofy and energetic individual with peculiar habits. Based solely on his personality, many question how Mirio is one of U.A.'s top students. Mirio has a very optimistic attitude and can almost always be found smiling. His character is what led Sir Nighteye to believe that he could be the one to replace All Might as the symbol of peace. Mirio is known for his odd sense of humor. His jokes range from corny to puerile, occasionally making a fool of himself for others' enjoyment. One such instance was when he stuck his clothed butt through the bushes as a puppet when introducing Class 1-A to Eri. Mirio does not allow his laid-back nature to cloud his judgment or impede his dreams of becoming a hero. He has proven an extremely hard worker, turning a near-unmasterable ability into one of the world's most powerful Quirks. Mirio is constantly looking for ways to improve his skills and tries to work toward his goals by accumulating different experiences to learn from them. Knowing he can't rescue everyone, Mirio chose the hero name "Lemillion" because he aspires to save at least one million people. Despite Mirio's uplifting personality, he can suffer from failure just like everyone else. He has an excellent understanding of hero protocols and can control his emotions proficiently to see the bigger picture. Mirio is also extremely brave and, in contrast to his laid-back nature, he is experienced in dealing with dangerous people and is not easily scared. Mirio is considered U.A. High School's most powerful student. Because of this, he is the leader of the Big Three U.A.'s best students, along with Tamaki Amajiki and Nejire Hado. Mirio, in particular, has earned enormous acclaim due to a combination of extraordinary technique, excellent fighting ability, and a charismatic personality, to the point of being considered a contender for the No. 1 spot among Pro Heroes and, at one point, a potential successor for All Might as a wielder of One For All.[14] His abilities garnered the attention of All Might's former sidekick, Sir Nighteye, who personally trained Mirio to the elite status the young hero now possesses. His mastery over prediction, inhuman physical abilities, and incredible Quirk render Mirio unrivaled in battle. The phase-shifter used his top-grade abilities to defeat eighteen out of the twenty students of Class 1-A, including some of its elite students. Mirio's greatest strength is incredible mastery over his near-uncontrollable Quirk, to which he is often considered invincible. Mirio can showcase meticulous precision on when and where in his Quirk, Permeation, should be active while performing swift moves. For those reasons, guarding oneself against his attacks in combat is borderline impossible. Thanks to rigorous training, Mirio was able to master instant transportation through the repelling property of his Quirk, being able to adjust the direction and positioning of his falling body to control the trajectory of his ejection, as well as using prediction based on experience to resurface himself next to targets, allowing him to strike them from any angle. For an outside observer, Mirio gives the illusion that he is somehow teleporting because of his apparent disappearance and reappearance at various spots, which happens almost immediately. Mirio possesses a great deal of physical strength, so much so that it appears supernatural. A single punch to the stomach was enough to incapacitate each of the Class 1-A members and break Overhaul's arm. In the battle against Overhaul, Mirio had the yakuza leader completely outmatched in terms of brute strength. Mirio possesses heightened speed. He took out over half of Class 1-A in about six seconds. This is mostly due to the warping ability of his Quirk, but Mirio showed great footspeed when he caught up to Overhaul and Chronostasis in only a few minutes after entering their hideout. Despite his carefree and laid-back personality, Mirio is very astute. Thanks to Nighteye's training, Mirio possesses deductive skills that allow him to predict his opponent's movements and fighting ability accurately. When he faced off against Class 1-A, Mirio decided first to defeat the long-distance fighters, knowing they would be the most troublesome, before subduing the remaining students who excel in close-quarters combat. As he and Izuku were on patrol and encountered Overhaul, Mirio successfully avoided suspicion while maintaining his friendly demeanor. Mirio's unwavering will, brave heart, and heroic spirit are some of the most remarkable aspects of his character that make him a true hero. Having dealt with many dangerous individuals, Mirio has become impervious to fear and intimidation, allowing him to overcome overwhelming threats and situations with sheer tenacity. Mirio's Quirk allows him to become intangible, letting him pass through any tangible matter; he can phase through walls or the ground, as well as let enemy attacks pass through him harmlessly.